I've had that happen too. I don't know why. One thing that worked a couple of times was to drink a quart or more of warm water, it needs to be pretty warm, but not so hot that you can't drink it quickly. The other solution is 100% effective, move to the Ozarks, find at least five miles of the roughest dirt roads you can, and drive anywhere from 10-30 miles to the nearest town with a public restroom. (OK Rowan, stop laughing)