Australian police are investigating whether officers ran naked round an unmarked police van as they travelled to a stag party.
The incident was reported by a woman who saw two men get out of the van at traffic lights in Brisbane on Sunday afternoon.
When police checked the licence plate number, they realised it was a police vehicle, Australian media reported.
The officers were said to be "very remorseful".
They were reportedly from the elite Special Emergency Response Team, used in situations involving explosives and hostage negotiation.
Commissioner Bob Atkinson said: "There is no excuse for this."
Queensland Police Union president Ian Leavers said that due to the nature of their jobs, the officers were usually on call 24 hours a day and did not usually drink alcohol.
"Their actions on Sunday are completely out of character and they are very remorseful," he was quoted by the Brisbane Times as saying.
Queensland Police Service ethical standards command is investigating the report.
The officers could be charged with wilful exposure and public nuisance, and face disciplinary action ranging from a caution to being fired.