Yo mama’s so stupid, she thought x-wings were for for boys and y-wings were for girls.
shouldn’t that be the other way around?
Correction: I am so stupid, I thought Xs were for boys and Ys were for girls.
Yo momma’s so gassy, Lando made back his fortune mining her.
Yo momma’s so fat, you could find the whole Colonial polytheistic pantheon of gods in her boobs.
It’s was funnier not knowing
Your momma’s so trashy, she likes sand.
yo daddy’s so gay he hates sand.
Your yo mamas are so funny, this mama got a much need LOL after a night of dealing with angst ridden teenage son.
Your momma is so fat, she reverses the polarity of the neutron flow!
The Neutron Flow.
sigh
That’s not your mother, it’s a man, baby!
So simple, yet so good!
Yo mama’s so hairy, Chewbacca fell in love!
Yo mama’s so sweaty, she put the moisture farmers out of business.
Okay, I’m new at this. Be kind.
Your mama’s so ugly, she put the eek! in geek.
Heh. Not bad, EZ.
Yeah! Positive reinforcement! I’ll have to think of more.
Your mama’s so fat, they had to expand the universe.
Yo mama’s so old and ugly, there was no Big Bang. The universe was just trying to get away from her! 
Yo mama’s so fat, Millenium Falcon hid in her mouth trying to avoid the empire.
Since we’re moving on to The Terminator story arc-
Your mama’s so ugly, the Terminator said, “I won’t be back!”
Yo mama’s so hot you sent your best buddy back in time so he could “hit dat thang” and you would be born.