V. The sound made by the testicles slapping against skin during the act of sex. This is best obtained by doing it doggy style! It could also work well with a good rough face-fuckin!
"Man I was poundin this bitch the other night all like Cheplap, Cheplap, Cheplap, Cheplap!!!!"
"My ole lady was layin on the couch runnin her mouth so I slammed my dick in it and my nuts went cheplap, cheplap, cheplap off her chin!!