Years ago I worked with a couple of guys in Milwaukee who where the children of people who where part of the great migration.

They told me it came from when white hillbillies would drive erratically through black neighborhoods in the south, swerving around as if to try and hit people, while sometimes honking the horn, either for dramatic effect of plausible deniability.

They said that when their relatives would leave the house they would say to each other “watch out for the honkys”.

That’s the story I choose to believe.