So...
I did a little research and found out how to make massive amounts of jizz.
Peter North recommends the following:
Celery-Eat a bunch of fucking celery. I've also been complimenting this with lots of fruits and vegetables, to sweeten the taste. Vegans have the tastiest cum, just so ya know. Also, drink a bunch of water, especially if you drink, smoke, etc. It'll flush the toxins out of your system.
L-Lysine(2/day)
L-Arginine(4-5/day)
Zinc(2/day)-This stuff gives your cum that nice Elmer's glue look that the ladies love so much.
Good luck, and happy skeetin'!