Why Do Guys Flush The Urinal Before They Piss?

I heard this guy do this while I was taking a dump at the U. today. Pisses me off because it confuses me so. Are you so impatient that you don't want to bother with touching a cold handle after you wanked your dick? Do you really think the entire flush swallowed down all your piss? I just don't fucking understand why you can't pee, then flush instead of flush, then pee. I ... it ... I don't understand!!!