I've heard the title many times...
...but I never DREAMED that this would be the premise of the show!
Do you mean that you thought by the title alone that the show was about someone dreaming of someone else named Jeannie?
The title is actually a play on an even older song and movie ("I Dream of Jeannie"). Because the title character is named Jeannie and she is a djinni, it becomes more of a play on that old title because djinn aren't supposed to exist, and her form is like a dream to Tony :-)