Aiming your ejaculate at the mattress instead of releasing it inside of a female, thus risking impregnating said female.
Lebron James' father should have performed mattresscide instead of bringing that useless human into the world.
by BLKJAK June 16, 2011
The sweat of a male's ball sack. Specifically in enough quantity to moisten the pants pocket lining and then leach into the pocket contents.
by BLKJAK January 11, 2012