Improv Everywhere

Last weekend I heard most of an episode on the NPR radio show "This American Life". Act 2 was about a group called Improv Everywhere that "causes scenes of chaos and joy in public places." This includes stunts such as repeating the same 5 minute scene twelve times in a Starbucks (prompting some patrons to ask if they're in a time warp), or entering subway trains without pants and pretending it's normal. In addition to these, the radio story dives deeper into a couple which are arguably more disturbing to the beneficiary/victim of the "mission".