"The hardest portion of English, I must say it: Idioms." Flula Borg
Tuesday, April 11, 2017
Apparently back in the day hunters would affix a decoy pigeon to a stump or to a stool at some point it seems to lure birds within their shot. But people aren't sure about how that evolved into what it was used for in the 19th century, criminal activity. Read all about the thoughts on this phrase here.
Today when the phrase is used it is more widely known to indicate someone is a police informer or a decoy/lookout for criminals.