verb: The act of using one's anus to "inhale" (reverse farting) the vapor from the "chuff" cap of an RDA (rebuildable drip atomizer) of a vaporizer (i.e. vape pens, mods, etc.) and having another person "butt chuff" the vapor cloud from the other's anus.
"I just butt chuffed a cumulonimbus!"
by Chuffuluffugous February 12, 2015