This article is from the Shenanigans FAQ, by Michael Moncur altshen@REMOVETHIS-starlingtech.com with numerous contributions by others.
Although most shenanigans are done by "ordinary folks" and among
groups of friends, there have been attempts to organize groups of
hooligans for the purpose:
Random Student Organizations (RSO's) - These are rumored to exist at
many colleges and universities. They are devoted to "randomness",
which usually involves doing strange things just to confuse people.
As such it qualifies as a shenanigan.
Unfortunately, RSO's aren't always the easiest people to contact.
If you're unsure if there's one at your institution... Start your
own. If there's one already you'll probably run into it.
The Cacaphony Society - This is a loosely-connected bunch of
organizations in various US cities (San Francisco and Seattle are two
that I know of.) They stay underground, since their activities are
occasionally above or below the law. They are interested in creating
cacaphony (confusion) and tend to do it by behaving strangely in
public. I've heard several of their escapades, and they're some of
the most elaborate and funny shenanigans I've heard...
Any specific information on either of these organizations will be
eagerly added to the FAQ.