Seeing Past a Forehead

Alright, listen up, buttercup. The joke is about someone with a HUGE forehead. Like, so big, it's blocking the view. It's funny because it's an exaggeration. You probably wouldn't get it since you're so smart, it's sad. Did you know that the average forehead is only like 2-3 inches? I bet yours is way bigger, you big-brain.