I think you'll find that the word itself has less to do with it and it's solely based on the age of whoever opened their word hole.
If your kid's friend says "that's sick!", your kid will agree.  If the next day you see something and tell your kid "that's sick!", they'll look at you like you've lost yer ever lovin mind.  
It doesn't matter what you say, you'll be uncool to the youth for years... right up until they grow up and move out.  THEN you're the most wicked awesome person on the planet because you have food, and a washing machine that doesn't have a coin slot.