The person who created this sign prides themselves in being an agitator to the point where they think it's their job. JOKE EXPLAINED.
The quote marks on this sign are where the comedy lays here. It shows that the sign creator sees the security guards as being largely ineffective. JOKE EXPLAINED.
What's funny about this sign is that there is a perceived extreme threat (the shark) that is given as a reason to do something small and annoying (peeing in the pool). JOKE EXPLAINED.
I'm just going to say it. I love where they started from with this, so all of these are going to get an A.
This sign is an 'up punch' toward the self superior people who wear sunglasses indoors. In doing this, it is using those people's sense of self superiority to frame them as inferior. JOKE EXPLAINED.