Because they don't like random people knocking on their doors
They Rocked their doors.
You don't let her out.
Anything with curry in it.
An Alley-Gator
Knock, knock, knockin on Heavens door
Burglars don't knock!
Hijabba the Hut
Lots a candy.
Dind Dong
Someone knocking at your door for no apparent reason.
The mafia doesn't like witnesses.
You let it sink in.