The cock of a guy who's hung like a horse.
Girl to her friend: "I hear that guy over there has a real slammer. Lets try talking him into a threeway."
by danisdan January 03, 2005
when getting head, you are not pleased with what u are getting, so you grab her by her hair, pull her off ur dick, hold your boner in place, and you slam her head on your dick repeditively. forcing a better blow job.
My girlfriend gave me such bad head, i had no choice but to summon a slammer on her
by Kalan Scott (Dream team) January 25, 2005