Imagine this
The name is revealed.
Then you go one step further.
Imagine secretly obtaining the name of somebody important to your participant.
You begin revealing information about that person.
Perhaps you eventually reveal their name.
They think the routine is finished.
Then you show them that person's initial physically burnt into your fingertip.
Or strip the premise right back.
Someone simply thinks of an initial.
You reveal it.
Then prove the impossible by showing that very letter burnt into your skin.