Quote from Joey in The One with the Home Study
Chandler: What the hell are you doing? Joey: Well, you wouldn't let me in, so I thought you were in trouble. Chandler: Well, we're not. Joey: But you called me "Bert." That's our code word for danger. Chandler: We don't have a code word. Joey: We don't? We really should. From now on, "Bert" will be our code word for danger.