What were they thinking?

Top CBS executives approved a musical skit where Janet Jackson would expose her breast during the MTV-produced Super Bowl half-time concert.

"The decision to go forward went to the very top of the network," a well-placed source explained from New York.

The groundbreaking scene came during the most-watched television broadcast of the year -- and during the dinner hour for the nation's west coast viewers.

In a press release before Sunday's game, CBS's sister outlet. [VIACOM's] MTV promised "Janet's Shocking Moments."

"I'll get you naked by the end of this song," sang performer Justin Timberlake, moments before he ripped off Jackson's top, exposing a bare breast -- the nipple covered by a tassel.

CBS's main New York switchboard was immediately bombarded with complaints about the stunt, network sources said late Sunday.