Effect:
A banana is used as a hammer to drive a spike into a board.

What You Need:
- a banana
- a nail
- a board
- liquid nitrogen in a Dewar flask.

What You Do Before the Show:
- You put a banana into liquid nitrogen to freeze it. This may take more than several minutes.
- You predrill a hole into a board

What You Do During the Show:
- You put the nail over the hole in the board.
- You use the banana as a hammer.

What is Happening:
When a soft object like a banana is frozen to liquid nitrogen temperature, it becomes solid.

Hazards:
- Liquid nitrogen is at about -190 deg Celsius and there is a risk of severe frost bite. Handle with insulated gloves.
- The frozen banana must also be handled with insulated gloves.

Patter:
Don't tell the people what has been done to the banana until after you do the trick. Predrilling the hole (hidden with sawdust) makes it easier.