Emergency bathroom need in flight   

Flight from DFW area to Jackson Tenn.  VFR initially but after climbing several times ended up on IFR at 11,000 over solid ovcst. Picked up great tailwind allowing the nonstop to Jackson. Approx 40 miles northwest of Memphis copilot advising urgent need to pee and medical condition meant holding for another 20-25 min not possible.  Found water bottle, full of course, in cockpit.  I indicated, not to brag, that I personally would not fit inside, not knowing his particular girth.  I drank the water, and he found a knife to cut the small top off the plastic bottle, which made the empty bottle very flimsy.  Fortunately smooth air allowed the copilot to refill the bottle too near the top. I shot the ILS to the runway at Jackson, breaking it just above mins, and made the smoothest touchdown (wheels) to the runway.  Asked the tower for a short delay, while the copilot deposited his  needs on the centerline.