I needed something similar for a track I was working on. What I did was I grabbed everybody in my house (I have 6 roommates) and I just had em yelling on the mic at the same time. You need a crowd cheering, you should be able to find a decent sound effect to loop easily. Quick search on google turned up this:

http://www.partnersinrhyme.com…..unds.shtml

Grab one, loop it for 60 seconds and you're set.