as exact translations, usually don't work anyway
Isn't that the beauty, though? It's just the idea or tradition that gives it the meaning.
Like this is an old one "jak tobie powiem co sie stalo, to chyba okocis sie"
or how about:
"czym sie nie naje, tym sie nie nalize"
"to nudne jak flaki z olejem"
There are some funny phrases and they don't even have to be risque or adult to be entertaining : D