Eat Your Hat
When you're so wrong about something that you feel like your face is on fire and you're stuck eating your hat like it's the worst meal ever.
"Eat your hat, you idiot! You lost to a kid!", after losing a spelling bee.
"Eat your hat, you failure! You can't even draw a straight line!", after a failed art project.
"Eat your hat, you piece of trash! You got beaten by a grandma!", after losing a dance-off.