You're so skinny, you swallowed a meatball and thought you were pregnant!
Meatball Pregnancy Scare Pranked Me, Dude?! XD
Explanation
Explain Bear
Alright, listen up, buttercup. You're so dense that this joke needs 'splainin'. It's sayin' the person is so skinny that a tiny meatball makes 'em think they're havin' a baby! Get it now, Einstein?