Cater Casting occurs when a film is cast with too many recognizable stars - say as with Ocean's 11, 12, and now 13.
Look at any billboard for Ocean's 13. Who do you see? The stars, George Clooney, Brad Pitt, Matt Damon, Andy Garcia, Al Pacino, Don Cheadle, Berney Mac? Nah. With so many stars in the film, each individual's "star power" is diminished and you start to see what looks like the catering crew at any 4-5 star Hotel in Los Angeles.
The film, Ocean's 13, is an example of Cater Casting.