The hair string was so believable that MGM had to issue a note when delivering film prints to theaters warning that the hair in the film is a gag and yet there have been reports back then about how many projectionists were fooled by the hair.
I envy anyone who's gotten a chance to see "Magical Maestro" (1952) with an audience solely because of this one joke. This entire short is Tex Avery throwing as much shit at the wall as possible to get a laugh, and it works wonders.
@Gilition
Now that is amazing. I remember seeing it as a kid and being fooled by the hair also and finding it great. Gotta love Tex Avery and what a mad genius he was. Based on what I read, he seemed like such a humble guy and had that quirky sense of humor up until his death.
@Animated_Antic
He did seem like a very humble guy. Joe Adamson said that he didn't have an ego as he would never credit himself for his genius and would always say "we". Though he wasn't as humble towards the end of his life as he grew bitterly depressed towards the end. It's very sad.
@Gilition
There are 2 jokes that wont make sense to a modern audience, the hair in the projector and a member of the audience getting up from their seat and being told to sit down or some other variant