A slang term amongst certain internet communities to denote an egregious degree of wrongness, incorrectness, or inaccuracy. The phrase was coined in mid 2005 when someone organized a viewing of Akira Kurosawa's film "The Seven Samurai". Unforunately the listing advertising the showtime of the film was from 2003.
The Mars probe crashed because the flight team didn't convert english measurements to metric? Man, that's not just wrong, it's Samurai Wrong!