look up any word, like donkey punch:
 
1.
1. The act of having a two girlfriends at the same time without them knowing about eachother

2. When a girl tries to start a relationship with a man she knows is in a committed relationship
1.

Bro: Who is jake dating, Tara or Ashley

Bartender: both, he's sidebitching

2.
Donna: why are you chasing jake if he has a girlfriend
Tracey: I don't know, I'm just sidebitching
by Promeo April 30, 2014