I've learn to piss standing up myself when I was 10-something.
It saved me from a lot of troubles, notably because girls in the bathroom take fucking forever, and I barely care of my indies get, you know, soiled myself. With little training most girls could piss standing up, it's a real lifesaver.
So yeah, when I was prebubescent I used to fool people around, especialy since most people wouldn't like stare at a kid pissing, now it depends weither or not I dress boyish or not and hide my hair with a cap and chest is not visible enough.
Fun story, once there was a guy who found me out despite anything, and he got an instant boner and couldn't piss, he had to move to the seal ones lol.