Shake it more than twice and you're playing with it...
I find I have to shake more when I'm pissing at public urinals. Damned if I know why. Maybe I just notice it more.
when I'm done, with my other hand i push upwards on the area between my balls and my a-hole. This shoots another bit of pee out that otherwise would dribble out after I left.
Learned this when freeballing, but do it by habbit now. no more pee stains