Now what

A man had just settled into his seat next to the window on the plane when another man sat down in the aisle seat and put his black Labrador Retriever in the middle seat next to the man. The first man looked very quizzically at the dog and asked why the dog was allowed on the plane.
The second man explained that he was from the Police Drug Enforcement Agency and that the dog was a 'sniffing dog'. 'His name is Sniffer and he's the best there is. I'll show you once we get airborne, when I put him to work.'
The plane took off, and once it had levelled out, the policeman said, 'Watch this.' He told Sniffer to 'search'. Sniffer jumped down, walked along the aisle, and finally sat very purposefully next to a woman for several seconds. Sniffer then returned to his seat and put one paw on the policeman's arm.
The policeman said, 'Good boy', and he turned to the man and said, 'That woman is in possession of marijuana, I'm making a note of her seat number and the authorities will apprehend her when we land.’
'Gee, that's pretty good,' replied the first man.
Once again, the policeman sent Sniffer to search the aisles. The Lab sniffed about, sat down beside a man for a few seconds, returned to its seat, and this time he placed two paws on the agent's arm. The policeman said, 'That man is carrying cocaine, so again, I'm making a note of his seat number for the police.'
'I like it!' said his seat mate.
The policeman then told Sniffer to 'search' again. Sniffer walked up and down the aisles for a little while, sat down for a moment, and then, racing back to the agent, jumped into the middle seat and proceeded to crap all over the place. The first man was really disgusted by this behaviour and couldn't figure out how or why a well-trained dog would behave like that, so he asked the policeman, 'What's going on ?'

The policeman, fidgeting nervously. replied, 'He's just found a bomb.'