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3.
two people thinking of having sex with each other.
1: whoah, you could cut the sexual tension between them with a knife
2: they're so having mental sex
by itoldyouiwoulddoitromyyouoweme December 09, 2008
 
1.
the communion or penetration of one's mind into or with another's mind, can often be akin to thinking of one another in a "sexual" way to some greater or lesser extent-- or just taking in the push and pull of one another in the form of thought tag.
When she picked up a carrot, he winked his eye-- engaging in mental sex while discussing the price of tea in China at the restaurant.
by mmm August 22, 2003
 
2.
mind games
Kelly just enjoys the mental sex. She loves to screw with your head.
by Chas April 19, 2003