Ted’s Toilet

My Uncle Ted invented a time-traveling toilet.
Shit makes it go forward in time, and piss makes it go back.
“Just sit down, do your business, and flush,” said Uncle Ted. “The plumbing takes care of the rest.”
“What if you do both?” I asked.
Uncle Ted smirked. “I’m not sure. Either the toilet will work out the math, or you’ll be ripped apart by a paradox wave.”
The next weekend, my girlfriend got sick on Jager-bombs and threw up in the toilet.
I haven’t seen her since.
Which really sucks, because it was her month to pay the rent.