Here's one that can act as a trick, bar bet, or competition: Bet somebody that you can drink an entire bottle of beer from a bowl with a normal soup spoon (or tablespoon, whatever) faster than they can eat and swallow one normal slice of unbuttered bread. It doesn't take a whole lot of practice to win with the beer.
Variants for your competition: two bowls, two people, carbonated beverage instead of beer (because kids) so you still have to contend with fizz. Compete! Or present the challenge as-is, and let the competitors choose bowl or bread. The one who chooses bread is a fool. Just make sure they are "normal" slices and not weight-watchers-bread-thin, or like massive cuts off of a colossal loaf either.