When you're looking at porn and your parent's walk in on you and your wireless mouse gives out.
Dude 1: Shit.
Dude 2: What?
Dude 1: I was on the computer looking at porn, and I thought I could get away with it but then I got mousefucked.
Through ignorance or incompetance, putting your job on someone else's shoulders.
Dude, I just got a call from someone who was talking to Mr. X, and he didn't fix the problem. Now they're bugging me about it. He mousefucked me on this one.
To screw one over or take advantage of someone in a subtle (and usually very quick) manner.
"I was changing lanes and that little punk mousefucked me (cut me off)"
The act of letting a mouse crawl up your ass, stimulating it. Mostly gay men/ lonely gay men do this.
Gay Man: Oh man! Last night, I got this killer mouse fuck. It really stimulated my rectum and prostate!