The Dick Van Dyke Show (1961)

Season 5: Episode 3

Rob and Buddy are working late, and keep thinking they hear a metallic voice saying ""Uhny Uftz""! The explore a supposedly abandoned office somewhere in the building, and find a somewhat 'mad' inventor (complete with a taciturn and vaguely menacing assistant) who has constructed a toy flying saucer. It works quite well, except that, instead of saying ""Merry Christmas"" as the inventor intended, the saucer only says ""Uhny Uftz"".