When the race or ethnicity of a character in a story is changed to an ostensibly more "palatable" or "profitable" ethnicity.
(A common practice in Hollywood, where the most coveted roles are frequently given to white actors to play, even if originally, the character was a person of color. Aspiring actors of color are marginalized and may have to play "racebent" bad - guy characters that were originally white.)
Paramount is racebending the the characters of The Last Airbender--Sokka's going to be played by a sparkly sparkly vampire!
Are they really going to be racebending Sosuke Sagara into Zac Efron?
Jackson Rathbone's helpful guide to racebending: Pull up your hair and get a tan.
Dee Dee Ricket's helpful guide to racebending: You don't have to wear a big African thing, just put a scarf around your head and you'll be a Ukranian peasant. (And Koreans should wear kimonos!)