Unsuspecting folks react to outlandish situations as hidden cameras roll. `Smile,' they're told, `You're on `Candid Camera'.' This forerunner of reality TV got its start (without the camera) on radio, in a show called `Candid Microphone,' which moved to TV in 1948. `Camera' (the name changed in '49) has aired on ABC, CBS and NBC, as well as on cable and in syndication. Peter Funt continues his father Allen's eavesdropping legacy in an hourlong version of the classic show on PAX.