From here:

A Sydney police officer has told a court he secretly filmed himself having sex with women to prove himself to younger colleagues.

Senior Constable Marc David Osborn is facing three charges of filming a person engaged in a private act for the purpose of obtaining sexual gratification.

The 42-year-old from Gladesville Police Station told Downing Centre Local Court today that he bought a clock with a hidden camera online in August last year, a week before the first offence.

He said he was working with officers in their 20s who would brag about their sexual relations.

Osborn said he was worried his colleagues did not believe him when he discussed his activities outside of work, so he played them the secretly filmed footage to show he was "one of the boys".

The court heard Osborn met the women through online dating sites.