Having lived with my mother my entire childhood (at least the bit of it, where I had left the potty), I never quite got to understand the point of standing up while peeing. As a matter of fact - I found out that due to the structure of the human body, peeing while standing left you with a lot of drops in the underpants - not very sexy. If you've gone to the toilet just a couple of times during a night out and manage to get it on with some chick.
I'm a proud I-sit-while-I-urinate kind of person, and I actually trained my father into doing the same (like a dog who's been trained to use a kitty litter box)