when you have a girl laying down, and u crouch over her face and she has your balls fully in her mouth. While ur balls are fully in her mouth, you take ur boner, pull it up, and let it fling down and slap her face. That is a jabber slapper.
This can be dangerous, as it can cause an unwanted reaction, making the girl bite your balls off.
Dude, the jabber Slap i gave Konica left a welt on her face. Needless to say, she is pissed.
Yesterday, when i gave my girlfriend a jabber slapper, the tip of her nose impacted with my penis pretty hard. It still hurts.