We used to have milk challenges. Find somebody really competitive (like me, because I tried it). Bring up this challenge. Tell him that if he can drink a gallon of milk in 20 minutes, then keep it down for another 10 minutes, he wins $20. It doesn't cost him anything to try it. You could even offer $100. Don't worry, you won't lose your money. From my understanding, and from what I've seen first hand, it's impossible. I heard a story of a guy that gave this challenge to a number of people. He even gave them an hour time limit. He never had to pay out the $100. He said that one person drank the whole thing, but couldn't keep it down. Something in the stomack will reject too much milk. I heard that the opening to the stomack won't close, and it will reject the milk.
This is what will happen 100% of the time. The person at some point will drink too much milk, and throw it all up. I got through about half the gallon before I had to give up. Within a minute I was throwing up in a trashcan. Looked like a white waterfall.
The second guy to try it drank damn near the entire gallon. He was about half a cup away. He was a pretty big guy, and said that he would have no problem doing it. He never quit. As time was running out, he lifted the carton to drink the last bit, then BOOM, milk all over the place.
The third try was a guy and a girl. This girl must have been 100 lbs, so we knew she wouldn't have a chance. She tried it with chocolate milk, like it made a difference. She gave in after about a 1/4 of the carton, then she threw up. The guy got about half way through when he threw up.
The last time I saw it done, a guy got two half gallons of Nesquick. This guy decides to chug the whole thing really quick, and try to hold it down. Not a bad idea. If he drinks it all in 2 minutes, and holds it down for 10, it's just 12 minutes of holding down all that milk, instead of 30 minutes. He smashes through the first carton in a minute. I'm thinking there goes my $20. He picks up the second carton, then BOOM, Nesquick all over the place.
Try it at work. Nobody will ever take your money. But it's probably best to do it off of company property. We did it at a park across the street.
I've also heard it's impossible to eat six saltine crackers at one time. I think it dries out your mouth, and you can't swallow them. I heard that you can't eat two slices of bread in a minute. Same reason. Before if you try it. Don't want anybody to choke. Have a glass of water ready.