In laws ‘teasing’ about my age

What’s the difference in their ages? Is your MIL older than FIL or younger? This seems a weird obsession.

This, no reaction whatsoever

It's an old joke and wasn't funny when it was new, so it sure isn't now.

Delivered deadpan

I would just turn it back on them and say but my life is beginning at 40. I'm loving it, just settling into my prime!
Not much they can say to that.
I feel for you though, my family can be the jokey, but cutting types

They sound like morons and very boring. Offer to buy them a subscription to The Times newspaper (or any paper ) on- line so they can be better informed in general and you can have a proper conversation about something else (like world affairs) for a change, It really does sound that senility is setting in and they are heading back to second childhood if they are repeatedly saying this and think it funny.

The retorts on this thread are killing me 😂😂 use all of them OP

Sometimes leaving the room can be a good move. You don’t have to flounce - just say “excuse me for a moment”, leave, and don’t come back until you feel like it.

Just say 'it could be worse, I could be 60".

'MIL, FIL, ever since I turned 40 you have been bleating constantly about my 'advanced' age. Do you mean to upset me? Do you mean to embarrass me?'
'It's just a joke'
'I believe I have made it perfectly clear that I do not find it amusing in any way. I ask again, do you mean to upset me?'
Keep insisting that they admit what they are trying to do. It turns the tables back on them and focuses on their poor behaviour. Unless they throw a tantrum -which also helps to pin poor behaviour on them- they'll have to back down and will probably stop doing it. Or, you go NC again.
'This now feels like bullying and I don't want to spend time around toxic bullies.'

The fact that you say you were no contact before as MIL is a bully , shows me clearly they’re not larking around , they want to upset you with constant digs ..
I’d go back to no contact..
No one needs an arsehole in their life , not to mind two !..

A friend of mine once told me , if you keep company with someone that when you’ve left their company you have feelings of anxiousness, negativity, well then it’s time to remove yourself from these kind of people..Period ..
It was with regard to a different “ friend “ , she was always passing comments, digs , hurting my feelings with sly remarks..
I took my other friends advice, & I messaged her a very nice , civil message, explaining the reasons as to why our friendship would not be continuing, & I never saw her again & was all the better for it..
That was 20 years ago …

Agree. Maturity doesn’t necessarily come with age. Clearly, the 40+ and the 60+ here haven’t the wisdom that comes with age. I can see that you feel bullied but happiness is a state of mind. Be secure with your age and move on.

Ask them with concern, “are you worried about ageing? If you are, we can talk about it. Make plans if you want to for the eventuality” Any comeback they have, you can say “you seem overly preoccupied with age, hence I asked”

I wouldn’t address it directly but I’d definitely sign them up to every email and promotional material I could for every older age related product/ issue that I could. Think incontinence, stair lifts, damart catalogue, care homes. But then maybe I’m just petty 😂😂

I'd be tempted to say, "Yeah, but I'll always be younger than you!" with a laugh. And then change the subject. If they don't shut up, ask DP to have a word and tell them to give it a rest because it's boring.

With my in laws a cold silence and a raised eye brow would let them know I wasn’t happy about their joke - can you try something like that?

Tell them that you want to have a chat about something a bit sensitive. Say that you’re worried about MIL as you’ve noticed she keeps telling the same ‘joke’ over and over and you think maybe they should speak with her GP about possible memory issues.

They're not taking hints so just tell them directly. "It was funny the first time or two, it's just old now."

Maybe suggest that they should get some dementia tests done at "their age" as they seem to have forgotten that you do indeed know how old you are but that the fact they raise it every time they see you is causing you some concern about whether they have dementia.

Right. Here's what I'd do. Treat them like OAPs in a very, very deadpan fashion. Constantly. They come round? Open the door and immediately cry 'watch your step'. Help them to an armchair. Whip out a blanket and pop sit over their knees. Speak LOUDLY AND SLOWLY. Lots of nodding / head tilting / encouraging SMILES when they reply. Serving them dinner? Cut it up into little pieces for them. Maybe offer to tuck a napkin into their collar. Push their chair in for them. Going out for a walk? Ooh not sure about that. Terribly uneven ground. Maybe invest in a couple of walking sticks and try to press these on them. Basically treat them like they're 100 and you're terribly concerned about them. They'll soon get the message.

Come back with something like “This joke is almost as old and tired and the pair of you! The fact you think it’s still funny is the real joke!” Or “oh god, are we still doing this joke, or is dementia kicking in…..the joke stopped being funny after the 20th time” cue the eye roll and reach for your phone and just scroll looking very bored!
This stuff pissed me right off! It’s definitely a form of bullying!

"Dear me, jealousy's a terrible thing". Directed at your DH, like you're really sorry for her.

Either avoid seeing them. Or when they start on about age roll your eyes and say oh not this again. Can't we talk about something else.

My ex mil joked about my age more times than I cared to remember, I told her that as she was 32 years older than me, I'd buy her a prepaid funeral plan for her birthday as she'd need it long before me.
The jokes never occurred again.

That's exactly what they're doing. Next time say: 'God, will you ever stop being so jealous!?' And just keep repeating this. If they refuse to stop, I'd just stop visiting them. Let your DH handle it.