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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

My sister, my bed, her ONS

118 replies

Laptopfangirl · 28/09/2026 16:36

I rent a flat in central London. I was away this weekend with work, and my sister asked if she could stay as she wanted to go out with some London friends. Fine. Not the first time.

I got back late last night and basically went straight to bed. This morning I woke up to discover a used condom in my bathroom bin. She brought a man back! She is single, so I can only assume it was a ONS. I have no issue with her having one night stands at all, but for God's sake clean up the mess! The bedsheets haven't been changed, the bin wasn't emptied. There were tissues in there as well which I presumed were just for makeup and regular cleaning but now God knows what else crosses my mind.

And to make it even worse I think (but can't be sure) that the condom was actually mine! Which would have meant them going through my bedside drawer (which also contains cash and God help me my vibrator!!).

I know my sister will consider it harmless but she brought a strange man back to my flat, shagged him, didn't clear up the mess and had me sleep in the same sheets!

Clearly AINBU to be slightly pissed off at this. But what level of anger is reasonable? A text jokingly calling her cheeky, or volcanic fury, or something in between?

OP posts:
QueenietheGreat · 28/09/2026 20:34

@Laptopfangirl
Don't ever let her stay over again
She's knowingly extracting the urine
If you're in Central London especially
She can book a cheap hotel room somewhere can't she??

Elsvieta · 28/09/2026 20:39

You knew your sister was coming and you left your vibrator where she might see it ...?

Anyway. Showing some anger is perfectly valid. Nothing wrong with telling her pretty sternly that when you say she can use your flat you mean her, not some randoms (of either sex, shagging her or not) you've never met.

Do you know exactly how much money was there? Any missing? Checked your jewellery box? If any valuables have walked I'd definitely be heading more for "volcanic".

comealongdobbeh · 28/09/2026 20:43

My level of anger at her complete inconsideration and using my home in that way would mean rescinding the invitation and never allowing her to use it again.

Laptopfangirl · 28/09/2026 20:46

Elsvieta · 28/09/2026 20:39

You knew your sister was coming and you left your vibrator where she might see it ...?

Anyway. Showing some anger is perfectly valid. Nothing wrong with telling her pretty sternly that when you say she can use your flat you mean her, not some randoms (of either sex, shagging her or not) you've never met.

Do you know exactly how much money was there? Any missing? Checked your jewellery box? If any valuables have walked I'd definitely be heading more for "volcanic".

My vibrator was in my bedside drawer where it lives.

Nothing is missing that I can see.

OP posts:
TheRobotsAreComing · 28/09/2026 20:54

I'd message her with an open question - what happened on Saturday then? See if she spills the beans. If she does, then you have to express how that kind of disrespect has made you feel. I'm sure she'll cringe at herself and apologise as most of us would!

If it's the 1st time then you can't go off the handle but you can whack a boundary straight down so it nips it in the bud.

TFImBackIn · 28/09/2026 21:00

Pallisers · 28/09/2026 19:29

I'd be really angry at this. Not changing the sheets/cleaning up is disgusting. But I wouldn't be happy with a man I didn't know being in my home either - without even a request for him to stay.

I agree with this. I wouldn't find it funny and I would be angry with her. That's your safe haven and she's brought some random into it without knowing how trustworthy he is. She didn't even change the sheets!

Sunsunsuns · 28/09/2026 21:02

Really grim.
Has she really so little self respect as to leave your bed used like that?
Bloody hell, grim.

RockinCara · 28/09/2026 21:03

I think I’d be messaging her and asking if someone else was in the flat with her on Saturday night, see what she comes back with.

ps, I think this is a totally normal thing to discuss with friends or mumsnetters before launching an angry tirade at your sister.
and most people I know have pubes, albeit well trimmed!

Imonmyownhere · 28/09/2026 21:07

Laptopfangirl · 28/09/2026 16:36

I rent a flat in central London. I was away this weekend with work, and my sister asked if she could stay as she wanted to go out with some London friends. Fine. Not the first time.

I got back late last night and basically went straight to bed. This morning I woke up to discover a used condom in my bathroom bin. She brought a man back! She is single, so I can only assume it was a ONS. I have no issue with her having one night stands at all, but for God's sake clean up the mess! The bedsheets haven't been changed, the bin wasn't emptied. There were tissues in there as well which I presumed were just for makeup and regular cleaning but now God knows what else crosses my mind.

And to make it even worse I think (but can't be sure) that the condom was actually mine! Which would have meant them going through my bedside drawer (which also contains cash and God help me my vibrator!!).

I know my sister will consider it harmless but she brought a strange man back to my flat, shagged him, didn't clear up the mess and had me sleep in the same sheets!

Clearly AINBU to be slightly pissed off at this. But what level of anger is reasonable? A text jokingly calling her cheeky, or volcanic fury, or something in between?

OP, please forgive me as I know this has nothing to do with your story but every time I see your thread title I think of The Thief, His Wife and the Canoe!

42goingon14 · 28/09/2026 21:15

Urgh. She really should have washed the sheets. I’d message her and say I’m pissed off and she better not do it again.

I’d feel the same if she’s spilled something on your sheets FWIW - I couldn’t care less that she had a ONS but surely she realises you’d rather not sleep in the bed after so then the logical conclusion is that she thinks you should change the sheets and not her.

DuchessOf · 28/09/2026 21:19

QueenietheGreat · 28/09/2026 20:34

@Laptopfangirl
Don't ever let her stay over again
She's knowingly extracting the urine
If you're in Central London especially
She can book a cheap hotel room somewhere can't she??

Where are you getting "urine" from?

EveryoneUsingOutro · 28/09/2026 21:24

Ablondiebutagoody · 28/09/2026 17:05

There was definitely cum in the condom? She may have used one on your vibrator

Oh vom! That almost feels worse!

EveryoneUsingOutro · 28/09/2026 21:26

BillieWiper · 28/09/2026 17:39

Sorry but to me an adult is entitled to bring an ONS back to any room they've been given access to overnight. Unless explicitly told no guests. Unless it's a family home with kids there etc.

You knew she was having friends over. Friends can be a very loose term. If you didn't want the potential for an ONS you should be said no guests allowed.

She could allege an ONS she'd met that evening was a long term partner or claim someone she knows well is a near stranger. If something went wrong. It is a risk you take saying she can host pals at your place.

She didn’t say she was having friends over. She said she was going OUT with friends.

EveryoneUsingOutro · 28/09/2026 21:34

TheRobotsAreComing · 28/09/2026 20:54

I'd message her with an open question - what happened on Saturday then? See if she spills the beans. If she does, then you have to express how that kind of disrespect has made you feel. I'm sure she'll cringe at herself and apologise as most of us would!

If it's the 1st time then you can't go off the handle but you can whack a boundary straight down so it nips it in the bud.

I like this. See what she says. Then tell her your rules. Or key back!

EveryoneUsingOutro · 28/09/2026 21:36

DuchessOf · 28/09/2026 21:19

Where are you getting "urine" from?

Means taking the piss. Taking advantage.

Damnloginpopup · 28/09/2026 21:50

I've just hurt my face raising my eyebrow so high. She might have used your vibrator being offered as a better option?

Okay...

Londonrach1 · 28/09/2026 21:53

Yanbu. A stranger in your house. I wouldn't allow her ever to stay in your house without you there again. Also she needs to change your sheets

BillieWiper · 28/09/2026 22:17

EveryoneUsingOutro · 28/09/2026 21:26

She didn’t say she was having friends over. She said she was going OUT with friends.

And unless explicitly told otherwise I'd imagine she could have some of them back to the flat. Which she did.

MandemChickenShop · 28/09/2026 22:21

tell her you set up a camera in the room and the footage is rather interesting, that should wind her up and make her think twice

WaryCyanStork · 28/09/2026 23:15

Am I the only one wondering how closely you were inspecting a used condom to realise it was yours? Envy

But yanbu, having sex in your bed and not changing the sheets is awful. I'd definitely not be letting her stay again.

Besidemyselfwithworry · 28/09/2026 23:18

Couldyounot · 28/09/2026 17:01

Wow. Cheeky and skanky in one move.

This
🤮

EveryoneUsingOutro · 28/09/2026 23:34

WaryCyanStork · 28/09/2026 23:15

Am I the only one wondering how closely you were inspecting a used condom to realise it was yours? Envy

But yanbu, having sex in your bed and not changing the sheets is awful. I'd definitely not be letting her stay again.

Presumably it was the empty packet that alerted OP to the same brand ….. Confused

Laurmolonlabe · 28/09/2026 23:51

There is not much you can do about it, and there isn't any point in making a fuss. All you can reasonably do is not allow her to stay again, don't mention why , but if she complains about not being able to stay tell her why.

DuchessOf · 29/09/2026 00:26

EveryoneUsingOutro · 28/09/2026 21:36

Means taking the piss. Taking advantage.

I've never seen it put that way. I thought there was some lurid element of the story I was missing 🤣🤣🤣

Bishbashbush · 29/09/2026 00:30

Similar thing happened to me but (thankfully) a thorough clean-up took place. It really damaged the trust and relationship between us though, because I didn’t find out the truth directly from her. Well she actually straight up lied to me. Something else happened too, which made the situation worse - Think neglect of a previously agreed responsibility to accommodate the unwelcome shagging in my bed.

I would have been incandescent to find physical evidence of a strange man excreting bodily fluids within my home to be honest. The thought of it was bad enough.

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