When you're at the gym and your bro sneaks a few extra pounds on the machine between sets while you arent't looking.
Bro 1: "Damn did that weight feel slightly heavier than the first set to you?"
Bro 2: "Nah bro, you got gain raped. If anything you should be thanking me."
When someone prevents you from going to the gym to make some glorious gains.
Bro #1: Bro, did you get your work in lastnight?
Bro #2 : Bro, I was headed out the door to the gym when my wife gain raped me with a honey do list.