A game that's amusing to watch if there's a large crowd.
Someone shouts out "sniper" and anyone who hears falls to the ground as quickly as possible, as if there actually is a sniper present.
Once everyone is down, the people on the floor aren't allowed to stand back up until the person who has previously shouted, "sniper" declares "false alarm, it's safe now".
Be completely amusing if it was a flash mob, such as the T-Mobile adverts.
-everyone falls to floor, waits twenty minutes-
Jack: "Oh, false alarm. It's safe now".