What episode did jerry say great googly moogly?

The phrase "Great Googly Moogly" is not actually a line from the show Seinfeld. It's a popular internet meme, often used as a reaction image or a way to express surprise or excitement.

However, Jerry does say the line "Good Golly Miss Molly!" in the episode "The Serenity Now" (Season 9, Episode 17).

While not the same phrase, it might be the source of the confusion!