Garnham, who posted a YouTube video of the incident filmed by Jade, said the clown intended to lift him and spin him through the air.
"From what I remember he didn't explain what he was actually going to do," Garnham told the Express newspaper. "He said, 'Push against the back of my legs' and that was the last thing I really remember."
"I just thought he was going to pretend to do something but not actually do it to get a laugh," Garnham said. "I thought he was just going to squirt me with water or something. It looked more like a wrestling move."
The video shows the trick take a turn for the worse when Granham lands on his back and is knocked unconscious.
Garnham said he was shocked when he watched the video and saw how circus staff moved him around while he was knocked out.
"I was unconscious right until they put me behind the curtain," the father said. "They lifted me out and I was manhandled -- they could've paralyzed me for life. I wouldn't have seen the funny side if I was paralyzed from the neck down or if I was dead."
Garnham, who said he wasn't asked to sign a waiver before the stunt, spent four hours at Royal Gwent Hospital before being released without injuries.
He said the Coles and circus officials have been in contact to apologize and offer him a refund plus free tickets for his family to attend the touring show in Carmarthen Saturday.
Garham said he doesn't have any hard feelings against Coles or the circus, but he believes the performance group should have paramedics on hand to deal with future emergencies.
"I'm so lucky," he said. "I could've died or been paralyzed."
