An utterly pointless gathering (often of High School students) in which the participants scream and shout until their vocal cords are scarred,for the purpose of "supporting the team." It is an attempt to make people happy about the backwards, stone age social system that still permeates our society, in which the biggest and strongest still remain on top, whilst those that have even the barest hint of intellect (read: nerd, geek, emo) are kept in the lower echelons in spite of the fact that it is them that drive society forward.
douche bag: Dude, there's a pep rally today. Let's show school spirit
intelligent person: no... i'd rather not support a social system that went out of date back when humans invented agriculture.
Long version: Someone who believes that "creativity" and "individuality" is the highest point which man can achieve, despite the fact that they provide no valuable service or advancement to society as a whole. They are little more than entertainers who have the gall to say that they are more important because they find "meaning in everything." Usually imbibe mass quantities of drugs. Often despise scientists for being too "shallow" or "narrow minded."
Scientist, dragged to art museum by a group of well meaning friends: "I see no point in this. It's a bunch of liquid pigments splashed randomly onto a large canvas."
Artist: "But, can you not see the passion infused into the painting? The inherent desire to escape conformity through abstract expression?"
Scientist: "No... and if this is escaping conformity, then why are there 20 more of these, all by different people?"
Artist: "Uhh... SHUT UP! YOU'RE SHALLOW AND NARROW MINDED! YOU'RE JUST A SERVANT OF THE MAN!"