They did that on MTV's "Jackass" show. I think three people tried to down the whole gallon in 5 minutes. Pretty gross as it regurgitated out their noses...
Try two glasses of Maple Syrup in 15 minutes!! I havent done that much but in school we used to drink a cup. Kinda like doen shots at the bar. If nothing else its one hell of a sugar rush.
Try eating 3 packets of sugar one after another.
Oh yeah, and don't use that Sweet-n-Low stuff, it'll make you puke. Go with pure, original, 100% REAL sugar.