For us guys, it's really easy to pee in the shower in the middle of the night. Since it's such a big target you don't need to turn the lights on, so your bathroom lights won't make you more alert. When you shower in the morning it will get clean, just grab the shower head and spin it 360 degrees to hit the shower wall.
When I lived in a rental house I cut a tiny hole in the window screen and peed out that at night, but I'm in an apartment complex now so that doesn't make sense anymore.
Peeing in the sink is an option as well, but you do need to be sure to run the water for a few seconds. If you leave piss in the trap it can start to stink. If you think it's gross at all just splash water on the sides of the sink.
For anyone who gardens, here is an excellent article on how to utilize urine as a fertilizer:
http://www.nwedible.com/how-to-use-pee-in-your-garden/