Nude Sunbathing Dude Sent Packing Outside Alessandra Ambrosio's Home

Naked and NOT afraid is what went down outside supermodel Alessandra Ambrosio's house Thursday ... drawing a swift response from 4 cops -- who clearly pulled the short straws.

Some guy mistook Santa Monica beach in SoCal for the South of France, because he stripped down buck naked and planted himself in the sand near Alessandra's crib -- twig and berries in the sand, for the most part.

Anyway, that's illegal in Cali, so Santa Monica PD pulled up to bust the guy who seemed completely unfazed by Johnny Law ... even as the officers slipped on their rubber gloves to go to work.

Law enforcement sources tell us the guy told cops he was merely drying his clothes -- and apparently his cheeks -- in the sun. The officers told him that's a no-no, and he had to go. Sorry, bro.

We'll say this ... the guy's ass definitely NEEDS some UV, and maybe that's why the cops cut him some slack. After they handed nature boy his clothes, he slipped 'em on and walked off into the sunset.

Beans and frank covered by pants. No cuffs, no arrest.