Sticking pennies into tree trunks is supposed to take away any illness that you have.
By pressing the coin into the tree trunk, you give your sickness to the tree.
However, taking any of the coins out will pass the illness onto you.
This is an old tradition in and around England that dates back to the 1700's.
I bet some of those old coins are amazing.
How do you just press a coin into a tree?
Can you use a hammer?