When you have a large machine gun in a First Person Shooter video game, and you hear an enemies footsteps, so you run around the corner and shoot left to right in a chainsaw fashion and yell/type RAMBO'D!!!!
I created this when me and my brother were playing Counter Strike on LAN, and I heard him, so I jumped out from around the corner and shot everywhere and yelled RAMBOOOO!!!
So instead of saying Rambo, I decided to turn it into a verb, like Rambo'D. Same as saying Pwn.
Machine Gunner: Dude, you got totally rambo'd!
Sniper: I know, I was not expecting that ramboness!