look up any word, like half chub:
 
2.
This is where you hide alot of your friends in a room where you know you will have sex, normally done at a party or gala event.

You take a girl (or rarely, a boy) whom you have no respect for into the room and commence having sex with her/him.

Right at the moment of climax, you give the prearranged signal and all of your friends emmerge laughing to scare and severly embarrass the victim
Dude, did you hear about Ellen?

No what happened?

At that party last weekend Cole Closet Monstered her! Matt, Jordan, and Evan were all hiding in the room
by SwissCanadian March 31, 2009
 
1.
a person of homosexual tendancies, but does not tell anyone for a long time. They spend a long time "in the closet" thus making them a closet monster.
guy 1: "man did you hear? Lance Bass finally admitted he was gay"

guy 2: "yeah it's about time, that fag was such a closet monster."
by Ryan July 27, 2006
 
3.
A person who acts goody goody in public but then when alone with a person of the opposite sex they.......LOVE THE COCK!!!!
Man, Jasmine is a massive closet monster!
by Pimpin November 20, 2004