Derived from the book, "Of Mice and Men" mouse can refer to someone dumber than Larry, particularly a blonde skank who thinks shes smart, but is dumb as fuck. A mouse often make damickey or outrageous comments that once made, are instantly used to pick on said mouse. The mouse typically makes friends with the smartest person in the nearby vicinity(The George of the situation), as it could not survive on its own. (What a dumb bitch). As we know, even with a smart friend, Larry eventually will be killed. Therefore, we can conclude that the mouse is worthless, and should be removed as soon as possible.
Guy 1: That girl that sits behind you in Calculus is so dumb.
Guy 2: Yeah, she is such a mouse.
Mouse: What't a mouse?
Guy 1 + 2: Nothing you fucking slut.
Later that day:
Mouse: George, I don't understand.
George: That's because you are a mouse.
Mouse: No, I am a female.
George: Shut the fuck up... Mouse.