In real life hundreds (perhaps a thousand) gathered when a Vaporeon spawned in Central Park. Life imitating a commercial.
Other real life Pokemon Go crowds.
500 people gathered in downtown Bellevue. People spread out all around the park and would shout out if a rare pokemon spawned. In the beginning of the video you can hear everyone shouting SQUIRTLE!!
Big Pokemon Go crowd at Santa Monica Pier
Video of Lemmings jumping off a cliff
Note - the 1958 Disney video of lemmings committing mass suicide was in fact entirely staged.
SOURCES - Youtube