look up any word, like spook:
 
1.
3+ boys and 1 girl in a dark room. Usually played with 12-16 year olds in their moms basement/dark closet.

The girl is given guy parts to put in her mouth and the whole point of the game is to guess who its it
Yo me kenny and steve played Who's in my mouth? with that polish slut alex. She totes guess it was me right away cuz i have the biggest cock.
by Alex Matysek November 12, 2006
 
2.
a sexual game played with 5 or more people. rules of the game are that everyone must not talk and turn the lights off. once that is done have everyone undress and start putting,their genitalia in each others mouths and have them guess who is in their mouth. no one can talk except for the person with the genitalia in their mouth. if the person guesses correctly then they get to go again. so on and so on until they lose. randomly select the next person to go.
*random person sticks he nuts into mouth of selected person.*
selected person: ughh its soo hairy.umm i dont know Who's in my mouth. come on tell me!
*muffled voice due to genitalia in mouth*
by Pwning like its 1999. February 22, 2010
 
3.
Popular party game played by straight frat guys put eachothers penises in their mouths and guess who's it is
Last night dude it was crazy we were playing who's in my mouth and i knew it was tony's foot long!
by Fratgame April 23, 2007
 
4.
When a group of homosexual males go into a closet or small room, turn off the lights and perform oral sex on each other. The object is to quess which male's genitalia was in your mouth before the lights are turned back on.
"Johnny, Tommy, and I played whos in my mouth last night... it was sho shilly!!"
by Flystiguy01 December 04, 2008
 
5.
A game played by a group of girls and guys in an area that can have the lights turned out and be complety dark. Girls on one side guys on the other. One person switches off the lights waits for a determined amount of time, enough for the girls and guys to meet in the middle and get their mack on. Then the lights are to be switched back on. Who ever is making out with another person has just discovered who was in their mouth.
Who's in my mouth? Smooch Smooch Smooch in the dark. lights come back on. Its that girl from 5th period i wanted to tongue
by Cjam3-0 December 02, 2010