Lindsay Lohan -- No Bra? NO PROBLEM!

It's official ... Lindsay Lohan can no longer contain herself after partying her face off in Brazil.

The 26-year-old actress ditched her trusty bra Saturday for a helicopter ride in Florianopolis ... after partying all night in Sao Paulo. She's been on the Brazil nightclub train ever since she flew south of the equator to promote some jean company last week, and she's obviously having support issues.