Hi...hope you don't mind me jumping in with some British slangs I've seen/heard.

Gobsmacked=Shocked
Snog=Kiss
Fag=Ciggie
Swot=Nerd
Willy=Penis
Daft=Stupid
Blimey=Oh God...what the hell!
Snooker=Pool
Crikey=Yikes...oh my God!

There's more that I ROFTL. I think British slangs are miles better than the Americans.