Clearly still seething about winger Reece Hodge's three-match ban for a high tackle in Australia's opening victory over Fiji, Cheika let rip after the match, his sense of injustice fuelled by the news that England's Piers Francis had escaped suspension for a high shot.
"I just don't know the rules anymore honestly," he fumed, given the gentlest of pushes to air his grievances.
"Our guy makes that tackle he gets suspended - the English guy gets off."
"The referees all seem spooked - everyone seems worried about so much," added Cheika.
"I'm not sure why, the players aren't worried. The administrators are spooking the referees and they're becoming ultra-cautious about everything. It's affecting everything else on the field."
Australia decided not to appeal after Hodge became the first player cited and banned in Japan following the incident in the 39-21 victory over the Fijians last weekend.
Hodge clattered into Fiji flanker Peceli Yato, who was left concussed and unable to return to the pitch in a game the Pacific islanders were winning. The Aussie winger went on to score a penalty and a try.
World Rugby announced a clampdown on high tackles before the World Cup, devising a new protocol to help referees decide whether to issue punishments.
Cheika launched a fierce defence of Hodge, arguing that his tackle didn't even merit a penalty.
"You've got to take care of the players not for the lawyers, but for the players," he said, after a setback that potentially puts Australia on a collision course with England in the quarter-finals.
"It's all sorts of crazy stuff. As a rugby player, a former player, I'm embarrassed."
- 'Terrible technique' -
Even Wales coach Warren Gatland had expressed sympathy for Hodge in the run-up to Sunday's showdown.
But Gatland played a straight bat when asked to comment after his Six Nations champions hung on for a huge win over the Wallabies that leaves them in pole position to top the pool.
"There's been a lot of criticism of referees and I don't want to be involved in that," he said.
"They've got a tough job out there, the've got things to follow. I think it's important the judiciary take care of those things. Decisions are made and we have to abide by them."
Asked about a Samu Kerevi forearm on Rhys Patchell that the officials deemed was only a Welsh penalty, captain Michael Hooper blamed the fly-half's high stance, saying: "That's a terrible tackle technique!"
Cheika needed no second invitation to follow up.
"It's funny because I thought I seen that tackle before," he said.
"Maybe Reece Hodge - not sure."
However, Cheika refused to back away from recent statements criticising World Cup referees after Australia narrowly failed to peg Wales back following a much-improved second half.
"We were looking good in the scrum tonight - got penalised," he growled. "I'm not sure, maybe Australians aren't allowed to scrum good, so I'll just keep it to myself. I know you're expecting me to go off so I'll just keep my powder dry."