You've bought a leopard, haven't you?

Apparently, the idea that lemmings throw themselves off cliffs in great hordes was completely made up by the disney company in the 50s. Who knew? Stupid disney.

Lemming populations go through rapid growths and subsequent crashes that have achieved an almost legendary status, largely because of the Walt Disney Pictures film, White Wilderness, which was produced in 1958 and reappeared on television at regular intervals for many years afterwards. White Wilderness popularized, using staged footage, the myth that during population booms Norway Lemmings become suicidal and leap en masse off cliffs into the sea

http://en.wikipedia.org/wiki/Lemming