I'm reading Ernest Cline's Armada at the moment. It features the urban myth of an arcade game recalled for causing hysteria in its players.

In the early 90's there was the Street fighter II myth about Ryu's quote : "you must defeat Sheng Long to stand a chance" this gave rise to the myth that Sheng Long was a character you could face after defeating balrog, Vega, Sagat and M. Bison without losing any energy...

Do you know any other such legends?