The act of cumming in your cupped hand and then lightly slapping your partner in order to splatter jizz over her face. An original move of Muscat Private School, Oman gentlemen. Usually performed when she tells you to NOT cum on her face.
A female who masturbates. ie. (slapping her cunt). Could be considered the female counterpart to a wanker. Its even more humorous to call your friend a "cuntslapper" than a "wanker" because it also implies that he's a female, and has a cunt that he enjoys slapping.
"hey joe, you cuntslapper! get in the car before we leave you behind!"
Person 1: "we had the week off of school, and the coaches still made us come to practice the whole week"