Okay, funny story coming up, so sit down, and enjoy the read:
We had a hick friend who enjoyed his dip... He would always come over to the house, grab an empty (or half-empty) bottle that was laying around, and spit his dip into that bottle...
I had a diet coke bottle that was still in use, unbeknownst to him. He grabs the bottle, spits in it, and sets it down.
I (later that day) grab the bottle, and took a giant gulp from it. I didn't realize what it was, until it was too late.
I rushed over to the bathroom, tried to throw up, didn't throw up, then grabbed some mouthwash, and poured some in my mouth... I accidentally swallowed the mouthwash, but at least I finally threw up...
A couple of days later, he comes over again, but this time I was prepared. I had, the day before, pissed in all of the bottles laying around the house, then poured them out, as an act of revenge against him... He never realized what I did, but at least I'll always know...