1. Create a new profile and name it whatever you want to, even if its already taken.

2. Then sign in your guest on another controller and join a game.

3. While the game is loading sign out your guest and sign in the profile you just created.

4. Now when the game loads your guest should have a name. If the host tries to boot your guest they can't because its a guest. A good way to annoy the host would be to create the profile with their name.