In a car, a seat heater that roasts your ass to the point where you think your cheeks are going to melt together.
friend - "Holy crap, dude, my new car has seat warmers, and they're total butt-welders!"
by joelh January 02, 2008
1 more definition
I was visited by a butt welder in the showers last evening.
by junior September 08, 2003