From ass + load.
assload (plural assloads)
- An amount carried by an ass or donkey.
- (slang, vulgar, US) A large amount.
2006, Leon Higgins, He She Black Widow, ISBN 9780615136714, page 192:
- I done made you a assload of money. You know fuckin' well, nobody else in this city could move as much 'caine as the Diablos.
2007, James V McKnight, Jammer, ISBN 9781434337702, page 78:
- I'm due an assload of credits and I'll die before I can get 'em! Who do I talk to?