I’ve heard the word “Beto” or its diminutive, “Betinho”, being used a few times as a sort of derrogatory word for a rich, posh person – someone the kids today would call privileged. I think I first came across it in 1986 A Série but didn’t really wonder where it came from. Apparently it’s from the early eighties when a Brazilian Telenovela called Dancing Days first aired on portuguese TV. There was a character in that called Beto, who was the son of well-off parents. He was played by Lauro Corona. The series aired in the late seventies and made its way to Portugal in the early eighties, so it still would have been quite a new word in 1986 when Nuno Markl puts it into the mouths of his protagonists.
Anyway, here’s a clip from the original series. It has strong eighties vibes to me, but I guess these trends don’t fit precisely into decades, do they?