The term "ass load" can be found in the Old Testament of the Bible. God tells Noah to bring an ass's load of grain for each pair of animal brought upon the arc. Thus an ass load is derived from the amount of weight that can be held carried by a mature, healthy donkey (ass).
The term is used again in the New Testament when Jesus shares the parable of Rosie O'Donnell's booty, it is cursed to weigh over 7 ass loads because she is an annoying, fat, and ugly bitch.
Your mom's jugs must weigh more than 2 ass loads.