The touching of one smokers lit cigarette to another's unlit cigarette with both cigs still in their respective owner's mouths. Used to light up in the absence of a lighter.
Dude 1: Got a light?
Dude 2: Nah, we can butt kiss though.
Dude 1: Gay, but do want a smoke.
The art of taking ones lips to the rim of another individuals well seasonedsphincter for a period of time long enough to flavor the participants lips.
Gavin decided after some foreplay to give <strangers name> a butt flavored kiss before he moved onto <strangers name>s chubby mountains for a taste of her salt water lake.