Time spent in physical, affectionate, skin-on-skin contact with a romantic partner. Can be a range of activities, including but not limited to cuddling, massages, kissing, and sex.
Wanting skintime is more broad than simply being horny, as one desires not necessarily sexual satisfaction but also touch-based emotional closeness, relaxation, and/or a cure for loneliness and stress.
I haven't seen my girl in 3 weeks... goddamn, I need some skintime.
Ruler of Lake Titicaca. Rumored to have a bunghole that gets very angry if it does not receive toilet paper. Cornholio the Great is often seen walking around with his shirt over his head and his hands in the air, chanting songs about his power, and his bunghole.
"I am Cornholio! You do not want to face the wrath of my bunghole, for I need TP!"
Butthead: Shut up, Beavis! (uh huh huh huh)
Beavis: Um, okay. (heh heh heh heh).