The Simpsons' episode ends the same way most Scooby-Doo episodes ends:
One of the protestors looks like Velma.
Chief Wiggum try to unmask Mr. Burns Scooby-Doo-Style, only to realize that he's not wearing a mask. He's just wrinkled.
Wiggum: Just a minute! This isn't Mr. Burns at all! It's a mask!
Wait, it IS Burns. Heh, his wrinkly skin, it...looks like a mask.