Yo’ mamma’s so ugly, that when the police saw her looking out her bedroom window, they arrested her for indecent exposure!
Your mama’s so fat that it negatively affects her self-esteem.
Yo’ mamma’s so dirty, she has to sneak up on the bathwater. 
Your mama’s so fat that when see sits around the house… she sits around the house.
When she hauls ass, it takes two trips.
I hate to admit this one took me a second to register. I can’t stop laughing. Kudos.
Yo mamma’s head so big, they thought she’d escaped from the Macy’s parade.
Yo mama’s so fat, she’s the fourth classical test of general relativity.
[taps microphone] hello…? Is this thing on?
Oh yeah? Well YOUR mama’s so OLD, when she was in school, they didn’t HAVE history!
And yo’ mamma’s so old she farts dust. Oh, yes she does!
AND yo’ mama’s so FAT, light BENDS around her.
Yo momma so fat, when she falls off the bed, she falls off both sides.
Ha!
Your mama’s so old, her first birthday cake didn’t have a candle on it, 'cause they hadn’t invented fire yet!
Your mamma is so old, when she went to church she said: “Oh, my dear Jesus, when did you get all grown up?”
You mama so stupid she thought she had to study for a blood test.
Yo mamma’s so ugly she went in the bank and they turned off the surveillance cameras.
Yo mamma’s so short her feet are in her driver’s license picture.
Yo mamma’s so fat when she backs up she goes “Beep! Beep! Beep!”
Yo momma so fat it’s easier to go over her than around her
Yo momma so stupid she studied for a drug test
Yo’ Mama so fat her *clothes *have stretch marks. . .
Yo momma so ugly they filmed Gorillas in the Mist in her shower.
Yo’ momma’s so fat all her clocks run slow!