Stands for "Ripping my fucking dick off"
Used in cases when one, usually of male gender, is greatly upset with a situation.
In real-life conversation, the motion of pretending to grab the penis and forcefully removing it from the body is used, but only in extreme situations.
If you're at a party, and some asshole takes the last beer, an RMFDO moment is at hand.
"Dude, I took the rent money and blew it on some Chinese hookers."