that'll teach you

[hecAteAMillionMincePies]

that'll teach you to mess around (got hurt)
for example.

Now, I'm no expert, but shouldn't that be that'll teach you NOT to mess around?

Does the person really need to be taught to mess around? I think not.

How many times do I hear that'll teach you TO, when it should be that'll teach you NOT to?!

Unless of course you are saying that'll teach you to be more careful.

Thing is, it's not rocket science so there's really no excuse - is there?

Or am I just being a miserable old cow with too much time on her hands?

Yes, you're right. There is an elided "not".

Still, it's better than "that'll learn yer!"

Worse - round ours you hear "that'll learn you"

Or 'he borrowed it me'

Or 'I won him at football' (really dear, is there room on your shelf for him?)

Ds is 3 and worryingly grammar correct (evil pedant mummy)

Everyone knows the correct phrase is "That'll lern ye", surely?

Reminds me of friend at parent evening overhearing father saying to teacher:

"I don't mind what you learn him as long as he gets plenty of football".