Forehead and Hairline Friendship

Listen up, chucklehead! This joke is about how someone's hairline is receding so far back that it's basically ancient history with their forehead. It's like saying their forehead and hairline have been buddies for a super long time because their hairline has moved so far back. I'm sure you can't relate because you look like you fell out of the ugly tree and hit every branch on the way down.