Invite Bonuses can be used to get a free room. Use the code "3142014" to get 2 free rooms as well as the wallpaper as shown below.
Summary
The invite bonus is where you give other users your code to encourage them to play the game. This allows you to play with friends!
The Invite Bonus allows you to earn a free room and exclusive items.
To get a free room, enter someone else's Player ID in the Invite Bonus tab. You can only do this once per account.
Whenever another player enters your Player ID, you'll be rewarded with a piece of the Classy decoration set. (Items can be found at Mojo's house)
Share your own Player ID in the comments section below!