Good question. Out of EVERYTHING I've ever eaten, and the fact that I'm an extremely picky eater, I think the grossest thing I ever ate would have to be actually, this one time....My friends and I were playing 'Truth or Dare,' and my dare was pretty much, I had on a blindfold, and they made a cup full of mixed condiments and random pasta. I have NO idea what was in the cup, but it was definitely the grossest thing that ever passed through my esophagus.
just kidding - i just remembered i once drank a mixture a couple of my friends made out of everything on the table at a Mandarin one time - the glass i think had water in it at first, but ended up with a considerable amount of soy sauce, jello, a squid, a packet of salt (including the wrappings), fortune cookie (including the fortune), ketchup, rice ... i don't even know what else. a lot of grossness anyway. (I only had a couple drinks of it though, not the whole glass.)