Once in a while I like to jack off with the great urge to pee. The intensity of the orgasm is amazing.
When you feel the need to relieve yourself, get out your favorite stimulation media (I use the freebie movies) and start stoking. The urge subsides a little when you get yourself hard. I like to stimulate myself for quite a while, bringing myself close several times. Then, usually when I've found an especially good clip, I let go with an amazing explosion.
Have fun jackin :-)