This thread is too funny!
I remember back in high school me and my friends used to say:
"S.L.A.P.P"
which means "Sounds Like A Personal Problem"
we were so "whack"
Some other ones where
"You get a 'rub' " (that is when guys would slap the back of another guys head..especially when they had a fresh haircut)
"Like Whoa!"
"Sippin on that Sizzurp"
"As if!"