Here’s how to do the undefined Club Penguin buddy cheat:
1. Clear your buddy list so that there are a few open spots. Try to have around five.
2. Gather a bunch of penguins who are willing to be your buddy on Club Penguin. Ask them to request to be on your buddy list.
3. Accept everyone’s friend request by clicking the envelope in the top left.
4. Open up your buddy list.
If everything worked out, you will have a list of undefined buddies! The bad thing is, this glitch will expire when you log out and the undefined will change to the penguin’s user name.