Talk

If they are a male teen:

Never take your socks off last when you get undressed in front of anyone.

I have one of each magi.

What to do if you get lost/locked out and don't have your phone/keys/money.

Very basic first aid (British Heart Foundation's Staying Alive videos, putting someone in the recovery position). Becomes increasingly important as they're around people starting to experiment with alcohol.

Cooking with mince - spaghetti bolognese, shepherd's pie and chilli all from pretty much the same recipe.

13yo ds had a life skills day at school recently.

He learnt how to weed, sow seeds and mow a lawn.

How to help someone having a heart attack, what to do if someone's choking and what to do if someone's been stabbed.

Some self defence moves.

He's not a very academic child and this kind of learning really appeals to him in a way that French, history etc just don't.

Do they know how to clean properly? I once absolutely lost it with a housemate (a guy who is a dear friend and a generally decent person) at uni because he hadn't lifted a finger in months and the state of the kitchen was depressing me. I spent a while yelling at him, then stormed off to my room to fume some more. When I calmed down enough to want a cup of tea, I found him in the kitchen holding a sponge and a bottle of washing up liquid looking a bit helpless. Further questioning revealed that he felt bad, thought I was right, wanted to make it better, but didn't actually know how to clean a kitchen. I then felt bad for yelling at him and ended up teaching him how to clean - shouldn't have been my job though, age 21.

Also memorising their home phone number, and at least one of yours and/or their DF's/appropriate adults phone number. I was shocked how many of our Guides (10-14yo) hadn't got a clue. They all said they didn't need to know it because it was on their phone. They were stumped when we asked what they'd do if their phone was out of battery/lost!

How to use a washing machine (and preferably an iron too)

How to order a round of drinks

What's the best remedy for a hangover (apart from abstinence)

How to say sorry

Oh these are all good.

How to hang out washing so it actually dries.

How to bleed a radiator.

How to use the tube map (if grown up in a city that doesn't have one- as will at some stage end up on a tube/metro/subway/etc)

And to develop the idea from magimedi: never put socks on before trousers. A man in a t-shirt, boxers and socks looks ridiculous.

I'm not sure I know how to bleed a radiator (delegate to DH).

How to iron a shirt.
How to admit they are wrong.
How to.open a bottle of champagne.

How to iron a smart shirt / dress (amazed when I went to uni how many couldn't)

First aid - I was taught first aid as a teen and it's proven useful (e.g. how to deal with choking, fits, collapse, bleeding, fractures and resus)

Creating a fire and cooking/staying warm without electric, oil or gas

Dealing with household emergencies (e.g. flooding, gas leak, fire)

Cooking from scratch - I was taught as a teen how to make edible bread with just a fire, flour, water and a stick

How to clean/maintain the house - including defrosting the freezer

How to accept responsibility for wrong doing and how to handle criticism correctly

How to say no and how to accept no (not just sex, but all sorts - drugs, jumping into a car where you can't trust the driver to go safely)

How to treat a wasp sting and other basic first aid.
Read music, swim, ride a bike ?

How to use a condom correctly.

Make a bed with flat sheets.

Drive

They would be mortified if I demonstrated condom usage.
<plots mortification>

Change a Tyre and treat a burn.

my mum once said that the most useful thing she could ever teach me is "always keep your gin in the fridge"

<helpful parenting>

To get a decent haircut

at BigKids

How to manage money, budget etc. How mortgages and loans work.

How to be streetwise and not fall for the cons out there.

How to quarter a chicken and make a sauce. Baking bread.
I've been baking since I was a young child, but my dad wouldn't let me move out of the house before he had shown me how to quarter a chicken and how to make a basic sauce.

How to assemble Ikea furniture - quite helpful when living alone.

How to use a drill.

How to clean the house, basic hygiene rules for kitchen/house.

How to do laundry.

Basic behaviour - shake hands when meeting people, how to sit properly at a table, eating properly/using knife and fork correctly.