Who coined the phrase "don't pee in my pool and i won't swim in your toilet?"?

Question

I hear it a lot. But I wonder who wrote it.

Answer 1

I like this one better:
Please don't throw cigarette buts in the urinal and we won't piss in your ashtray.
These are all variations on a theme - it's impossible to find out who came up with them first.

Answer 2

I like ::

WELCOME TO MY OOL

Notice there is no P in it...Please keep it that way.