You see a birdcage.
You see a little bird inside.
Notes
You can get this item by unpacking a Birdcage Kit. When you "use" a birdcage, the bird inside begins to sing and Yellow Notes Effect appears. Although, there's a 0.1% chance that the bird will die from a heart attack and this item will turn into a Birdcage (Dead). Killing the bird will grant you the achievement Oops.