Pissing with a boner isn't a problem for me, eventually touching the inner rim of the toilet is though. If it happens you can go straight into the shower, there's no getting around that.
On another note, we already have a lot of topics covered in here, but what about little games that you can play while taking a dump?
When I was a kid I used to play this game I called "destroy the alien base". Note that you need to take your shit before peeing in order to successfully play it. You also need a "silver tablet" styled toilet, without the water hole.
Nico, you might want to stop reading here.
Okay, so you take the shit and hold your pee in. The deuce is the alien base, place it like you want it, just keep in mind that it's the fucking enemy. So now your pee is a promising last fleet of human space pilots on a suicide mission to save humanity. Your goal is to either destroy the ammunition chamber of the base (random part of deuce) or the Control center of the alien base (random part of deuce). You might also resort to just causing as many alien casualties by really messing up their base, but that shit's dangerous. If you manage to cut off and flush away strategically important parts of the base, you win, if not, you can be held responsible for ruining humanitys last chance to escape slavery. It's important to not go easy on the aliens when you start your attack, the kamikaze pilots make the difference, trust me.
I haven't played this in a while although it never gets old, but I'm interested in other games as well.
PS: let's never meet in person please.