I told my friends that are gay that my hairline's straighter than he will ever be.
Straight Hairline
Explanation
Explain Bear
Alright listen up, buttercup. The joke is playin' on the word "straight." This dummy is sayin' his hairline is straighter than his gay friend, get it? 'Cause straight also means not gay? And you, friend, are probably the kinda guy who claps when the plane lands.