To pinch ones flow, as in a bad situation occuring, or someone causing a bad situation. A real flow pinch would be when some guy is going to the bathroom and another person grabs his dick and "pinches his flow. This phrase can be used in almost any bad situation
One guy is with a girl and is about to have sex with her, and his bro walks in and turns on the TV and starts to watch. The guy who is about to get some shouts back "Dude what a flow pinch"
by Flow Pincher January 28, 2009