"The Strongbox" Season 9, Episode 14

Kramer buys a strongbox due to some recent burglaries in the building. He tries to hide the key in Jerry's apartment, where Jerry keeps finding it. Jerry refuses to let a man into the building because he doesn't know him - then it turns out he's Phil, Jerry's neighbor. Kramer then hides the key in Phil's apartment where his pet bird eats it and dies. Kramer and Jerry then need to dig up the bird in order to get the key and open the strongbox to get Jerry's cuff links. George tries to break up with his girlfriend, but she won't accept it. Elaine dates a poor man, who she thinks is a superhero.