blue canary
n.— «Altschul said that the first responders to any terrorist attack would likely be police or firefighters. Like the canaries once used by miners to detect poisonous methane gas, the “blue canaries,” as police and firefighters are sometimes called, would probably suffer heavy casualties until the agent is identified.» —“Army giving cities fighting chance against chemical weapons attack” by Ron Martz Atlanta Journal-Constitution (Georgia) June 29, 1997. (source: Double-Tongued Dictionary)
Further reading
Megan from Savannah, Georgia, is curious about a phrase her father used: down cellar behind the axe, a phrase whose meaning she never quite understood. Down cellar, meaning “down in the cellar,” is common in New England and the Canadian Maritimes...
A Navy veteran recalls hearing the Southern expression fat lighter from his wife’s family in Troy, Alabama. It denotes an old, resin-rich pine wood that becomes highly flammable as it ages. Fat lighter is prized as kindling and often called fat...