RICHARD: No, no, they’ve already hung up. [phone stops ringing]
LORELAI: Okay, next time hold an envelope up to your head before you do that.
Lorelai refers to Carnac the Magnificent, a comedy role played by Johnny Carson on The Tonight Show Starring Johnny Carson, previously discussed. Carnac the Magnificent, dressed in a feathered turban and a cape, was a “mystic from the East”. When a sealed envelope with an unseen question was placed against his forehead, he would pretend to psychically give the question to that answer.
The humour would come from an unexpected question which followed a seemingly straightforward answer. For example, Carnac would give the answer, “Sis boom bah”, and the question would be, “Describe the sound made when a sheep explodes”.