So the punchline is… Pull out your dick and piss in her mouth because…

She’s a public bathroom?
I don’t think I get horny post comics.

This post is clearly horny but I don’t know why everyone is saying there’s no punchline. The punchline is that pissing in her mouth in the store is exposure therapy.

This is honestly funnier and more well-paced than like half the comics that get posted here.

Alternative read. They’re into watersports and do this at home. He’s holding it because he wants to wait to get home so he can relieve himself that way. She’s teasing him about being unable to make it home to enjoy it. It’s not actually a matter of being uneasy about public restrooms, just the much more understandable discomfort with that sort of activity in public.