Grassing out vocalizes the act of someone passing out or being overwhelmed and choking before, after or during present smoke caused by fumes induced by incinerated Cannabis leaves.
dude 1: first bong ever WHOOOOO I'm gonna get soo high
dude 2: go on man take a hit
1 minute later while dude one is Grassing Out
dude 2: WHoa bro he tots grassed out
The Dude: Far out man, far out.