Jack and Jill went up the hill so Jill could whack off Jack. Jill yelled out, "Jack, where is your sack?"
Said, "I'm not Jack, I'm your friend Nancy."
Alright, listen up, bonehead. So, Jack and Jill go up a hill for some sexy time, right? But plot twist! Jill thinks she's with Jack, but SURPRISE! It's Nancy in disguise. You see, it's funny because it's unexpected and kinda gay. It's a morbid take on a children's rhyme. You wouldn't get it, though, being the big dumb dumb you are.