Trivia: John Astin (Gomez), Carolyn Jones (Morticia) and Ted Cassidy (Lurch) are the only actors to appear in all 64 episodes of the show.
Trivia: Originally, Lurch was supposed to remain mute for the entire show. In the pilot, when the bell is first rung to summon Lurch, Ted Cassidy ad-libbed the line, "You rang?" This caused everybody to burst into laughter and from then on Lurch would talk.
Trivia: Although it was kept a secret for years, the part of Thing was performed by Ted Cassidy. He sometimes had to travel to the studio to do it, even if Lurch wasn't in the episode. Though in a few episodes, where both Lurch and Thing appeared in the same shot, assistant director Jack Voglin performed the part of Thing.
Trivia: Although everybody knows all of the Addams Family members' names, none of them had their now-familiar names when Charles Addams created them for the New Yorker magazine. It was when the idea was pitched to the television executives that the names were created. Coincidentally, the Addams Family and The Munsters debuted the same week, and were cancelled the same week two years later.
Trivia: Ted Cassidy (Lurch) was an accomplished organist, but only mimed playing the Harpsichord. Also, before he was Lurch, Ted was a weatherman.
Trivia: Producer Nat Perrin created the voice of Cousin Itt by reciting gibberish into a tape recorder and then playing it back at a higher speed.
Answer: Basically from what I understand, they stuck the innards of a small flashlight into the base of the bulb and put a little switch on it. When he put it in his mouth and bit down, his teeth would hit the switch, which would turn on the flashlight and made the bulb light up.
TedStixon