The Skin in Skinny Dipping

Me: What fun thing or two did you do over the summer?

Student 1: I went skinny dipping. Wait, what is skinny dipping? Is it when you go swimming in skinny clothes, like when they’re really tight?

Student 2: No it’s when you’re naked, like with your girlfriend.

Student 3: Yeah, it’s soooooo romantic.

Me: Um, no. It just means you swim naked.

Student 1: Oooooooooh, now I know why brother was laughing at me!!

Class: (laughing)

Student 1 (sincerely confused): But, if it’s not skinny clothes, why is it called skinny dipping?!

Student 4: Because it’s your skin. SKINny dipping. Duh!