Slang for a girl who just won't give it up.
Guy #1: I've been with her for over a year, and we still haven't had sex. She's impussible! What do I do??
Guy #2: Tool
The inability or impossibility of a straight man to get into a gay woman's pants.
He's kidding himself if he thinks that lesbian chicky babe is even remotely interested in him. He's on an impussible mission tonight, the tossbag!