I never answer knocks on my door
I get really annoyed when unexpected people knock on my door or call my house phone, my family has keys and if it's someone I know they'll probably call me anyway so there's no reason to check who it is because I know it'll either be someone selling stuff I don't want or a kid that wants me to give him a ball he just flew over my roof. Everytime I hear that annoying RRRRRRRRRRRRRRRRR sound I just sit quietly for two minutes until I sense they leave.