Let's see.
Average person produces 6 cups of urine per day. There are 16 cups in a gallon (128 fl. oz. / 8 oz.). 300*16 = 4,800 cups of urine / 6 cups = 800 days.
This guy has been saving his urine (assuming it's only his and nobody else's) for more than TWO YEARS.
Yep. This one definitely belongs in MNS.