You get a resizable invisible prim that you and anyone around can click and it will play random knocking on wood sounds.
This prim will attach by default on your head in a transluscent state, as seen in picture above.
While the prim is visible you can easily adjust its position and size as needed to cover your head or wathever you wear to cover it.
When the prim is position as you like then you can long click to make it invisible and long click again if you need to make it visible.
You can also use this prim to cover any other wooden item you want to knock knock and have fun :)
The prim contains only a copy-only script that plays the sounds. No actual sound files included.
Head cage on picture not included. Its name is B2L - Punishment Mask. You can get it here: https://marketplace.secondlife.com/p/B2L-Punishment-Mask/26376718