A fork of Rural Dictionary
When a guy is being a total jerk and is only thinking on getting with you. It usually comes with assgrabs and "accidental" boob touching, heavy flirting, and the occasional skirting.
How was your date last night? It was okay, he was being a total penisbrains though.
When you take your penis and put it in someone's eye socket
Guy: "I gave her a good penisbrain last night!" Guy 2: "Nice one!"