Miss USA Host -- Bush Out, Walberg In

TMZ has learned Billy Bush has pulled out of hosting the Miss USA pageant this Sunday due to some sort of stomach illness, and Mark Walberg (no, not the guy from the Funky Bunch) is now taking his place.

Walberg, who hosts "The Moment of Truth," is taking on the exhausting task of looking at 50 beautiful women in bikinis.

Well played, Mr. Walberg.