Here are some!!!:
Yer mom is so stupid she got trapped in a grocery store and starved to deathYer mom is so stupid she saw a schoolbus and chased after it thinking it was a gaint TwinkieYYer mom is so dumb she tripped over a cordless phoneYer mom is so fat she went swimmin in the ocean an a whale came up and started to sing: "WE ARE FAMILY!! EVEN THO UR BIGGER THAN ME!!!"