a dog in a bathtub
When you stick your balls up your girlfriend's butt and it feels like you're trying to put a dog in a bathtub and it's laughing at you.
My guy stuck his balls in my butt and it felt like I was putting a dog in a bathtub.
He stuck his whole sack in my butt and it was like a dog was laughing in a bathtub.
My man tried to put his whole junk in my butt and it was like a dog was fighting in a bathtub.