Yo mama is such a slut, she could get slapped by a pack of hot dogs and get pregnant.
Yo mama and hot dogs
Explanation
Explain Bear
Listen up, chucklehead. The "yo mama" joke is saying the subject's mom is super promiscuous. The joke exaggerates this by saying she can get knocked up by some hot dogs. I know you're probably as bright as a burnt-out bulb if you found this funny, but whatever, gotta explain it to ya.