v.: The act of touching somebody on the butt. It may have a gay reference if a guy touches another guy on the butt. This is not to be confused with gay touch-ing. Where as gay touching is with a group, butt touching is usually just a single, one on one, touch.
“Hey, you want to hang out later and do stuff, and by doing stuff I mean touch butt, and by touch butt I mean butt touch.”