first time caller longtime listener

A person who regularly listens to a certain talk radio program, but until today has never actually called in. You know them when you hear this phrase.

"Hi Ray, this is Megara — first time caller longtime listener — I'd like to ask the guest if..."

When someone delurks on a mailing list, they may say for humorous effect: "Long time listener, first time caller..."

As with talk radio, the claim isn't necessarily true. Trolls often pretend to be newbies in both media.