Yo Mama - Imaginary Friend
Yo mama so ugly, her imaginary friend played with other kids.
Yo Mama - Sandbox
Yo mama so ugly, when she was a kid, cats tried to bury her in the sandbox.
If I was as ugly as you were, I wouldn't say "Hi" to people. I'd say "BOO!"
While walking the red carpet, a celebrity turned to the paparazzi standing nearby. "This," she said, "I suppose, is one of those hideous representations you call modern art?" "No, madam," replied the paparazzi. "That one's called a mirror."
Yo Mama - Reflection
Yo mama is so ugly, when she looks in the mirror, her reflection ducks.