No chance you could get twenty-five people in the vocal booth and record them on a single track?

I wish, but it is a 4 x 4 (width) vocal booth!!

do 'em one at the time :)

Still creates a problem with too many tracks, right?

How portable is your recording system? You could move to a more open space and record them all if you've got a lappy.

Or a few at a time? You could uncomfortably fit 3 or 4 people in there (depending, of course, on how many headphones you can summon up. Accio headphones.) Record three or four of those tracks or something.

I don't know a mixing-end trick, though. Can't help there, sorry.

Run a chorus effect into a chorus effect and set each to generate an additional 4 voices. Gives you an effective 25 voices.
Just don't split them too much in time or it'll sound stupid.

Correction: more stupid than it would've done.

Do all things mentioned above, record 25 tracks, then bounce them to one and delete the originals to save disk space.

To get them tight, I would just select them all, cut them to the same place and use a very short fade in and fade out. All aligned perfectly and edited simultaneously. Maybe even let a couple of the up front ones stay slightly sloppy to give the realistic feel. I do this a lot with full band stops in music and it works like a charm if you do it right. Kind of like manual gating. Just another idea. :)

Otherwise... there has to be a harmonizer out there that can handle this. Or just line up a ton of pitch shifters with formant controls.

Record a bunch of your friends in front of the console - you included (bigger room, right?).

Do enough tracks until it sounds right.

Get lots of people and don't use the vocal both , use your live room or Garage or basement or living room or
whatever

Use a bedroom, whatever, and set up a condenser mic. you don't have to worry so much about vocal tonality, as the focus is more on intensity.

How about being cool enough to get on stage in front of a crowd and then getting them to do it?

Why fake it when you can make it?

Greener wrote: How about being cool enough to get on stage in front of a crowd and then getting them to do it?

Why fake it when you can make it?

Bingo!

I've put people into booths and also just done it en masse within a relatively quiet environment. Both techniques worked, but the second has always yielded me the best results.

YMMV.

I've found that its much better to double or quad track a small group of people doing this, around 4 people who all know the song very well.
This keeps it a lot tighter than using 10+ people.
More benefits of doing it this way include adding / removing tracks to increase / decease intensity.
Different processing on each track.
Being able to pan them individually.

Good luck!