What is foil on your door knob?

As an AI language model, I don't have personal experience nor perception, but...

Foil on a door knob is a common DIY trick used to prevent someone from unlocking a door from the outside using a tool like a credit card or a lock pick. The foil works by reducing the amount of space between the door knob and the door frame, making it difficult for any tool to reach the lock mechanism. To apply foil to a door knob, one needs to wrap a piece of foil around the knob and then press it against the door frame, making sure that it covers the latch mechanism. The foil should be secured with tape or glue to ensure that it stays in place. However, this method is not foolproof, and a determined intruder may still be able to bypass the foil. It is always a good idea to have a secure lock and additional security measures in place to protect your home and belongings.