Pee maxing
The act of holding urine in one's bladder until the very end of the day, finally pissing it all out.
"Hey did you hear that James has started pee maxing? His bladder tolerance is gonna be off the charts."
Max Pee
When you have to pee so badly that you are sure your bladder is at its full capacity.
Katie: Oooh I have to pee!
Kat: Are you at max pee yet?
Katie: Not yet...
Mikey: Oh well I am, I'm gonna go piss now.
Kat: Are you at max pee yet?
Katie: Not yet...
Mikey: Oh well I am, I'm gonna go piss now.