The heist went off poorly. Or exceedingly well, I suppose, depending on what the mugger was after:
Link -via Dave Barry | Photo: Flickr user Ambernectar 13
An unknown man approached a 62-year-old woman as she was walking her dog just before 10 a.m. on the 100 block of Dakota. The man demanded the woman she give him everything she had, and he said that if she didn't, he would kick her dog.
The woman handed him a bag and the suspect fled. Unbeknownst to the suspect, the bag she gave him contained her dog's feces.
Link -via Dave Barry | Photo: Flickr user Ambernectar 13
I think you would find it goes back way before the 1970s. Read Jan Harold Brunvand. He traces the similar "stolen specimen" story (urine in a bottle stolen by thieves) back to the 1930s and relates it to earlier stories.
of course, sometimes the events in ULs actually happen.