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2.
A gas mask fitted with a bong instead of a filter, the purpose being to smoke weed while wearing this mask.
We wandered around until we found a grassmask for sale. Zach and I bought and went home and got blazed as hell!
by Vindikation April 11, 2007
 
1.
A device used to smoke marijuana, usualluy fashioned out of a steam roller bong and a hose connecting it to a piece that covers your nose and mouth. A grass mask will completely fill your lungs through your nose as well as your mouth
"That grass mask kicked my ass last night."
by Old man withers August 03, 2005