About 99% of the time I have to piss after cumming, either from jerking off or sex. Mostly it's from jerking off, unfortunately.

I figured it was always just a natural thing, to flush the cum out of my dick. It may be 10, 20, or 30 minutes later, but it WILL happen.
It's actually a little harder to get the flow of piss started, and it tingles a lot at the beginning when the piss first starts flowing.
I'm cool with it though.