you with the face and I recently talked about how we sometimes shiver when we have to pee really really bad. But I’ve never shivered after peeing. That’s just weird. 
OK, looks like academia has at least glanced at this, here’s some links:
Academia 1 “It is my thought that the more desperate one becomes in response to a bulging bladder, the more of a general sympathetic outflow of action potential will be generated to keep you dry. This would include the release of the adrenal medulla catacholamines epinephrine, norepinephrine, and dopamine. When the opportunity arises to allow the parasympathetic side of the ANS to take over, the change in catacholamine production might be the cause of the shivering.”
Academia 2 "Actually, says Jon Cross, M.D., a neurologist at Jackson Memorial Hospital in Miami, “the shiver is a response of the autonomic nervous system.”
My god. Danalan & MidnightRadio, thanks for the links. I shoulda known Cecil would have hit on it at least once. And I knew my little friend could get me in trouble…but I hope I never wake up with a knot on my head from the porcelain maw.
A limerick:
There was a young man from 'Stanbul
Who soliloquized thus with his tool:
“You stole all my wealth
And you ruined my health
And now you won’t pee you old fool!”