It can be reused several times - until the paper is eventually torn
Do not creep up behind people and make a bang - I am not responsible for your actions and the consequences.
You will need a thinnish cardboard
Strong brown paper
Step 1: Step 1
Mark out the two diagonals with a pen or pencil
Fold the card along one diagonal - try to get a neat clean fold.
Step 2: Step 2
Place the paper triangle in position along the marked (unfolded diagonal) and fold the edges of the paper back over the cardboard and glue in place to the cardboard on the other side.
Step 3: Step 3
Then fold the cardboard square along the original fold. You will also fold the brown paper as well.
Hold the cardboard so that the pointed end of the triangle faces down and chop the whole thing down sharply - as if you were chopping something with a knife.
All being well the downward motion will push air into teh brown paper pocket - which will fly out with a very loud BANG.
You can then reload - by refolding and it's ready to go again.
Have fun but don't scare your grandmother