Fishing not allowed.
Ok, so I remember one from my youth times, hope it´s not too overused. here it goes:
A man is fishing in a forbidden zone, with a clear sign showing, when a police truck pulls over to confront the man. Seeing the officer coming in his direction, he hides his fishing rod, and silently watches the water:
man: Good morning, officer, is it something wrong?
officer: Good morning, do you know you cant fish here?
man: I am not fishing, sir, why would you think that?
off…