One who prevents or interferes with a Jehovah's witness trying to knock on someones door.
Curt placed a land mine underneath his doorstep today to knock block
the Jehovah's witness.
Chris answered his door naked to greet the Jehovah's witness
which caused the unwanted Jehovah's to flee his property. Chris; is the ultimate Knock Block.
Jehovah's Marty- "Lets go spread the word of our lord."
Jehovah's Pete- "Ok"
Jehovah's Marty- "OMG PETE... wait!, your leg is caught in a bear trap."
Jehovah's Pete-"We just got Knock Blocked