basically to have sex lying down, cannot be vertical
or doing the crazed dance of the time, also while lying down
also can mean 2 monsters having sex, lying down
by Paublo Sanchez June 30, 2006
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sex with a chick... fucking a chick, banging a chick.. that sort of thing
omfg! Their doing the Horizontal Monster Mash on my leg!!! (WTF?)
by teh_n00berx0r June 11, 2006
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