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1.
Euphemism for rectum or anus, specifically when referring to anal sex.
I went out with Jill last weekend and I stuck it in her coal-mine.
by Pook420 April 28, 2009
 
2.
A Coal Mine is an insult from a friend or family member that uses an embarassing or deep secret of your's to hurt or embarass you. Usually used in a large crowd (where it has more exposure to others.) or to use against you.
1. Bill doesn't have a girlfriend anymore because his brother Coal Mined him in front of her.
2. "Hey Bob, get me a drink."
"Why should I?"
"Hmm... Perhaps you've told me something I can Coal Mine you with."
by Buffalo Puppy July 25, 2009
 
3.
Where the people who defined school as hell end up
You know who u are
by Ozone May 06, 2004