eat a bag
It’s like saying someone has to swallow a bag of severed penises, or a bag of butt stuff, or even a bag of used socks from a landfill.
My friend said, 'Eat a bag,' when I spilled my soda on his shirt.
My mom said, 'Eat a bag!' when I got a D on my math test.
My dad said, 'Eat a bag!' when I asked for a third slice of pizza.