Dirty shotgun

Put a nug in your asshole.

Someone lights the nug, as you squeeze-in to suck the weed smoke into your bunghole.
Then the other person proceeds to put their mouth on your ass while you squeeze out(fart) the smoke into their mouth as they inhale.

“Hey, you two girls should totally dirty shotgun eachother, it’d be super hot!”
“One time I tried to dirty shotgun my bf, but he kind of sharted during, so I never did it again.”