The Marine Biologist (Season 5, Episode 14)
While George is off trying to convince his college crush Diane that he’s a marine biologist, Kramer decides to hit golf balls that he stole into the ocean.
When George and Diane visit the beach, they see a whale washed up on the shore, which means that it’s Dr. Costanza’s job to solve. In this last scene George explains his bravery in that moment, only to have saved the whale by simply taking one of Kramer’s golf balls out of it’s blowhole.