Yeah.... get out, dripping wet, and make a big wet mess to clean up, creating a slipping hazard so you can pee a few ounces, just to flush it down with a few gallons of water... when you can be "green" and just kill two birds with one stone.
Make a deal with you... I won't pee in your shower and you don't pee in my toilet.
Nasty! And what about the next person in the shower after you if all your pee doesn't get washed away? You might as well ask them to splash around in the toilet bowl.