A group of metal detectorists at a rally in a small South Yorkshire town were raced to hospital after consuming cakes spiked with cannabis.
Some 13 men and women fell ill at the rally in Doncaster on Saturday night.
A 48-year-old woman from County Durham was arrested then later released on bail in relation to the incident.
Editor of Treasure Hunting Magazine, Julian-Evan-Hart said it was a "dreadful incident" but he did not believe it was malicious.
Instead, he said he thought it was an "irresponsible, poorly thought-through joke.
"This isn't a poor reflection on our hobby, the dig organisers or anyone else involved the planning of the event. It's just a case of random lunacy," he told the BBC.
He said the cakes were homemade and had not been sold.
A number of medical staff were called to the scene to assist those that had unknowingly indulged in the illegal substance.
These included eight ambulances, a rapid response vehicle, two doctors, two clinical supervisors and a Hazardous Area Response Team.
Yorkshire Ambulance Service said two people were treated at the scene.
It said they received an emergency call just before 18:30 BST on Saturday to "reports of a number of people feeling unwell a national metal detecting event".
The 13 people, who came from across the country, were later discharged from hospital.
