The tune is only a dim memory, but we used to sing a song called "Atlantic City" which went:

I met a young girl in Atlantic last year
Who every bright morning would walk to the pier.
She'd dive in the water, it was smooth just like glass
And give all the people a view of her ----

Antics in the water clear up to her chin
And she'd never be drownded as others have been.

The girl had a brother who'd dive off the dock
And amuse all the people by shaking his ----

Fist at the crowd standing up on the shore
The same shore he'd stood on a moment before.

There were a couple more verses but I can't remember the setups for the "dirty" parts.