When you're smoking weed and you take a hit and you hold in 100% of the smoke from the inhale, exhaling *zero* smoke from the hit. Done in order to get maximum effect from the weed. Requires great skill and is worthy of respect from other smokers.
"Yo I was ripping a B with Joey Fatone the other day and he was totally zeroing every time ... insane!"
The video game that spawned all your base due to its crappy translation. It's actually very fun, though primitive and kind of hard once you get into it.