The action of two obese homosexual males inserting their genitals inside each of their navels. The position this usually takes place during is the classic 6to9 position that most females enjoy during lesbian sexual intercourse. (Basically, two fat guys shove their dicks into the other guy's bellybutton.)
Person 1: Dude, apparently Bob and some other guy pudgy slammed each other!
Person 2: Wait... WTF HOW DO YOU KNO- shh...... Don't tell anyone... Damn I'm going to slam him harder tonight...