A term coined in the roleplaying environment of Efnet dealing with the hypothetical idea that when one dies, they will go to 'Mun Hell,' where the characters the roleplayer played will do things to the player similar to what they did to the character. A player who was nice to their character is treated well, and a player who is sadistic to their character will have sadistic deeds done upon them. It is often stated that if one wants to have fun as a roleplayer, one should be afraid of mun hell (implicitly meaning that one has the most fun in RP by sticking their characters in situations the character would not enjoy.)
"I am so going to mun hell for this."
by Searcher Omega August 25, 2007