Your kid's so ugly he would make a Happy Meal cry.
Happy Meal Tears
Explanation
Explain Bear
Alright, listen up, buttercup. This joke is saying the kid is so ugly that even a freakin' Happy Meal, which is already pretty sad, would start bawling. Basically, your brain is so smooth, it could be used as a Slip 'N Slide for ants, ya hear?
DreamBlue
turns out he's your dad :)