Do you mean this classic version: http://www.dailymotion.com/video/xed64_hooray-4-hollywood-busby-berkeley_music ? (The vocal kicks in at around 1:38.)
If so, that was from the movie "Hollywood Hotel", and the song was performed by Benny Goodman's Band, and sung by Johnnie "Scat" Davis, Frances Langford, and others. Yes, that first high-pitched voice, (which sounds more like a woman to me), was actually a guy - Johnnie Davis.
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