jokkin

Literally has the same meaning as "joking" or "joshing," but is a combination of the two. Pronounced (JAWK•KIN), is generally used to ask a person if they have been fooling you, or to inform someone you have been fooling them.

"What the hell, are you jokkin me?"
"Yeah, I'm just jokkin ya, chill out!"

ttyl

Touched Tits Yesterday Late

Basically means that you got laid last night, directly stating that you touched some tits late in the day yesterday, or yesterday night.

Man, last night I TTYL'd!

You bitch, I was at home playing video games.

billy mill roundabout

British slang for the climax of male masturbation.

If that bloke keeps it up he's got 'imself a billy mill roundabout, the lucky wanker.