Miss Butt Brazil Model -- Andressa Gets Undressa'd on the Beach

You're looking at the 2nd best ass in Brazil. Yes, the SECOND best -- and it belongs to Andressa Urach ... who hit the beach in Portugal, and decided to do a little topless sunbathing.

Andressa was 1st runner-up in the 2012 Miss Butt Brazil pageant -- or Miss Bumbum as the locals call it -- a nationwide contest to find the country's blue ribbon rear.

Click through the gallery ... Andressa's boobs must be sick of taking a backseat to her ass ... 'cause they came out to play.

BUN FACT: The best ass in Brazil, according to the MBB 2012 judges, belonged to Carine Felizardo. Now you know.