A post-coital activity wherein the dominant participant ejaculates in his palm & then proceeds to slap the recessiveparticipant on the buttock with the same.
1. the act of screaming the word "jizz" while moving your arm in an overhead circular motion and connecting an open hand to another persons face. Usually resulting in the extreme anger of the individual receiving the "jizz" slap.
2. the act of removing a condom after sex and firmly grabbing the tip while full force slapping the condom over your partners face, resulting in an open ended explosion of your seminal juices over the persons face. If done hard enough a laseration of the skin will occur and seminal juices will flow into the cut.
It's when you cum in your hand and slap your partners ass. It is a loving gesture between two consenting adults.
It's also a great word to help you win Scrabble (as seen and defined in the liamkylesullivan video "Dirty Scrabble")
"Dude, I heard you and the freaky chick Martha went out last night"
"Yeah man, and when we got back to my place, I jismslaped her, like a boss"
"You're the man, bro!"