When a Jehovah's Witness comes to your door it sticks in your head and, if you're like me, you tell someone(s) "A Jehovah's Witness came to my door today, blah blah."
I know there's usually a negative connotation with these types of encounters.
Imagine the kind of impact we could have on people if we at least mentioned Jesus to one person a day/week/month. It'll stick in their head and they may spread the word, hopefully in a positive manner, to others.
Reminds me of Six Degrees of Separation. Be the vessel that brings people to Jesus.