A butterload is a really hard cum that drains the testicles of semen. Typically, a butterload happens when a guy hooks up with someone pretty close to his ideal fantasy.
Tool no. 1: Dude, that girl is so damn hot. She's way outta your league.
Tool no. 2: I know man. If I get to fuck her, I am gonna pop a fuckin' butterload. Cum for days, dude!