Crowds on Demand, as the name suggests, is a company that will organize a crowd for you, on demand.
The two main scenarios that require this service are: 1) You're an aspiring celebrity who wants to make it seem like people give a shit about you, so you hire some fake fans; or 2) you believe in a cause and want to make it seem like people give a shit about it, so you hire some fake protesters.
Unfortunately, I couldn't go along to see one of the company's fake fan events (as they're super secret,) so I went along to a fake protest they organized in Los Angeles, instead. While there, I sat down for a chat with Crowds on Demand's founder and CEO, Adam Swart.
For the rest of the story: http://www.vice.com/read/its-now-possible-to-hire-fake-protesters