Listeners were urged to call in with their guesses about the test results before Balzat read them out on air.
Ellis joked that he wasn't surprised his co-hosts had allegedly tested positive given they had been "fraternising" together.
"It's a bad social clique that we've got going on in this group. Thank God I've got my own friends."
Tolan replied: "Well stop selling it to us then and we'll be all right."
Holt told Ellis she didn't want to apologise to listeners.
"The only person who is listening who might care is my mum and she gives me stick about driving in cars with people who smoke illicit substances."
Tolan blamed his co-hosts after the announcement his test was positive.
"Obviously I've just been hanging around with the wrong people. I've been trying to escape from these two for almost a year now and contracts just keep you here. But after that result I think I've found a loophole."
MediaWorks spokeswoman Rachel Lorimer said the segment was a "lapse of judgment" and strong action had been taken against those responsible. "We would like to apologise to More FM listeners and anyone else who was offended by the segment. MediaWorks does not condone the use of illegal drugs."
"Appropriate and strong action has been taken with those responsible for the segment. The hosts were not responsible for the segment."
Lorimer said MediaWorks does not have a policy of random drug testing.
Holt, Ellis and Tolan refused to comment and referred questions to MediaWorks.