a diaper
A diaper is when a girl has a round butt that looks like she’s wearing a poopy pant. It’s like she’s a baby with a bubble butt.
My girlfriend has a bubble butt. It looks like she’s wearing a diaper.
My sister’s butt looks like a diaper. I can’t stop staring.
My crush has a bubble butt. She’s like a baby with a poopy pant.