This one is quite rude, you don't want to use it in public or you could get beat-up.
Means
Vai Tomar no cú"
or "Go f*ck yourself"
. Much better is to use the thumbs up symbol. Interestingly, when I took my diving class
they said to use this symbol for O.K., I wonder what Brazilian divers use?
Even though this gesture is rude I've often seen people gesticulate holding their hand that way (usually both hands). So I guess this gesture is rude only in the right (wrong?) context.
