For time and working with a partner, partner 1 only working on the odd minutes, and partner 2 only working on the even minutes:
125 chest-to-bar pull-ups
95-lb. push presses, 150 reps
95-lb. back squats, 175 reps
P1 work from 0:00 to 1:00 and rest from 1:00-2:00 while P2 works, P1 work from 2:00-3:00 and rest from 3:00-4:00 while P2 works, etc.
I stuck with it for about 2 weeks and never finished my entire gallon. Even though I never got through a gallon it did cause me to drink a lot more water and I felt better because of it. Yes, I had to pee more but I also felt more refreshed throughout the day and even after a vigorous workout.
How much water do you drink per day? Give it a shot and let us know how it goes!