From Canoe.com:
An airport security exercise went the way of a movie farce after TNT was planted in the luggage of an unwitting passenger instead of the bags of a security agent. The passenger arrived from abroad Friday night. At a friend's home, he found explosives labelled TNT had been concealed in a jam jar and placed in his bag.
The man called Quebec provincial police.
Officials said such exercises -- intended to test bomb-sniffing dogs at Pierre Elliott Trudeau International Airport -- are carried out every week.
So, to sum up, airport security not only couldn't keep their own agent's bag straight from a passenger's bag but their dogs still didn't find the (helpfully labeled) explosives and they released said explosives to a (thankfully) honest citizen.
Terrific. With all the airport security stories circulating its a wonder that more people aren't taking buses or trains.