I discovered Improv Everywhere several years ago and have enjoyed watching their flash mob missions “causing scenes of chaos and joy.” One of their best-known missions is the annual No Pants Subway Ride.
Awesome things like this happen more often in larger cities and almost never in Indianapolis — until recently. This summer I came across an improv group that was started on the IUPUI campus downtown: Dead Unicorn Society. I believe they are actually an official student organization on campus, now (or are working on that status).
They have had some good events so far. The most recent was a live version of Mario Kart Battle. Unfortunately, this mission was only for IUPUI students (or I would have participated!), but they have plenty of events open for anyone to participate in.
Their next event on November 18 is one such event. In honor of the new Harry Potter movie coming out on the 19th, they'll be performing wizarding duels around downtown Indianapolis. They have received a lot of “maybes” but need at least 10 confirmed individuals that can attend between 3 and 6pm, November 18. Unfortunately (again), I will probably not be able to participate due to the timing. If you're in the area and can participate, let them know!