A small strip of contact superglue on the side allows you to surreptitiously fix this in some hard to see spot on your postman's bicycle / scooter / van, as you engage them in some polite chitchat. As the adulterated delivery vehicle makes its rounds, dogs are alerted to the coming postman and make their preparations for ambush. Wait a few weeks until postman disappears on stress related leave, convinced that every dog in the world hates them.

Spend that time following behind your victim, giving cocktail sausages to all the dogs on the route until they view you as some kind of Cargo Cult God, like Prince Philip.