I was on Google Chat at work conversing with a friend, and my wife logged into my account at home and totally whacked the conversation!
Although to everyone else this means 'bad', it sounds like it should mean 'good' so we are changing the meaning!!
Whack now means 'cool, awesome, good, superb, fantastic' etc.
"That Ben and Jerry's ice cream is whack!"
Something that functions very differently than expected
PGPNet is whacked!
18 of something. A dozen and a half if you will..
You should eat a whack of dicks.
The idea that a person born today could be in the Cold War is whack.