If you have a bum good enough to bare in the latest social media trend, be careful - the outcome may be worse than sunburn.

This is the warning from police and travel and social media experts following a bare-bottom frenzy on Instagram.

"Making the world happier through butts," states the catch-phrase for Cheeky Exploits - which has gained over 166000 followers. The site wants travellers to upload snaps of their bare bums at various landmarks.

The travel craze - which has clogged news feeds with photographs of mooning travellers - landed in South Africa last week when a Bulgarian tourist uploaded her #CheekyExploit taken in Cape Town.

While Instagrammers have praised the cheeky travellers, the SAPS have warned that it would not tolerate "crimes against public order".

"The matter referred to would be an act of public indecency. If anyone is found to be on the wrong side of the law, as the SAPS we will take action and the person will face the full might of the law," said police spokesman Athlenda Mathe.

Thompsons Holidays spokesman John Ridler said posing for a nude picture at any public site or even a private hotel or resort was "not a good idea". "The law forbids such displays of public indecency and individuals could also find themselves at odds with the code of conduct at hotels."

Trend analyst Nicola Cooper said the new craze may lead to tourist hot spots laying down the law. He said Instagram users latch on to online fads to "gain attention and a form of self-differentiation from the masses".