When i was a kid i used to hold both legs one on side,one on the pedal and one in the air,then take my cock out and piss.Since i was sideways,with my back somewhat turned towards the seat,i was able not to wet myself while pissing.It was difficult to hold control of the bike though,because of multiple reasons.I had to drive with only one hand,since the other one had to hold the cock.Also,since all my weight was only on one side,i had to recline a bit to the other side so that the bike wouldn't fall.It's a difficult and dangerous method,and i pissed myself many times.But it's also fun to show off to your friends.