Known as mooning, the cheeky offence was previously punishable under other laws but is now banned under specific legislation across the whole of Victoria state in Australia, of which Doncaster, part of Melbourne, is included.
First-time offenders face up to two months in jail while repeat offenders could spend six months behind bars.
The amendment was one of more than 50 crimes included in an overhaul of sexual offence laws.
The updated legislation has been designed, in part, to separate pranks involving nudity from acts of sexual exposure.
The Summary Offences Act states that "behaviour that is indecent offensive or insulting includes behaviour that involves a person exposing (to any extent) the person's anal or genital region".
It specifically cites "mooning or streaking" as an example of such an offence.
The act also outlaws singing "an obscene song or ballad" and behaving in a "riotous, indecent, offensive or insulting manner".
The ban in the Down Under Doncaster comes just a few weeks after a naked woman was photographed strolling through our Doncaster town centre in broad daylight.