It's a tradition. One of us has to go.
5 seconds sound clip from the Addams Family Values movie soundboard.
You can hear this line at 00:05:01 in the Blu-ray version of the movie.
Quote context
[...]
- It is so. Everyone knows it. When you have a new baby, one of the other children has to die.
- Really?
- It's a tradition. One of us has to go.
- Well, they only need one boy.
[...]