Answer:
What has no hands but might knock on your door, and if it does you better open up?
People want it, and when they have it, they use it by giving it
A mechanism to discover who is following you.
What can touch someone once and last them a lifetime?
Come up and we go, Go down and we stay.
When is it bad luck to see a black cat?
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?