when you sneak up behind somebody (or jump behind them), stand really close behind them, then thrust your hips forward, so the person is caught off guard and gets sent flying.
this is a very fun practice, especially when the person who is zavathrusted is in a line of some sort, so several people are sent flying.
see also zavablocked
Samantha: so yeah I was just talking to my friends when all of a sudden Stacy pops up behind me and thrust me forward into the air!
Juan: hahahahah EPIC ZAVATHRUST!