When you drank three sodas and you really need to use the bathroom, this is an example of a time when you need a pee.
The urine that comes out and goes on a fire hydrant when a dog goes to the bathroom on a fire hydrant is an example of pee.
When you go and use the toilet and urinate, this is an example of when you pee.
When you are so frightened that you wet your pants or are afraid you will wet your pants, this is an example of when you pee from fright.
It's peeing with rain.