A dirty lapeedis is when a guy and a girl are engaging in sexual intercourse, and the guy pulls out and finishes off his load by jacking off. He tells the girl he is going to get it in her mouth with the intention of actually getting in there, but he completely misses and gets it somewhere else not even close to the girl. Quite common for guys with bad aim. The name originated from the movie Zenon Girl of the 21st Century, hence the name lapeedis. Somebody had tried to shoot Zenon with a blaster but was completely off.
Derek is coming over again today. I am sort of hoping he gives me a dirty lapeedis again cause I do not like the taste of his sperm.