I'm going to go with "brood of nerds" as well... and yeah, there's only one Vader in my fucking book. I imagine the conversation went like this:
"Alright, who's going to be Vader this year?"
*ten guys raise their hands*
"Now look guys, we talk about this every time, we don't need that many Vaders!"
"Hey, fuck you Brent! My mom spent three weeks making this costume for me and I'm going to wear it whether your stupid ass gives me permission or not!"
"Allright, Clarence, shit! Don't get all defensive, we'll have multiple Vaders, goddammit."
How far off the mark is that?