I suggest it more like and addition to the already existing Stamp Set "Expressões Brasileiras".

This expression is used when we're talking about untrue friendships, where the fake friend puts other in dangerous or embarrassing situations.

It's origin is from a joke from years ago, where one of two hunters, who are supposedly friend, asks the other a lot of absurd questions about a hypothetical situation in with an onça is in front of them and the hunter asked in turn, without much patience left in him, if his friend was really his friend or friend of the Onça, because in all the questions, general the response involved the other hunter being eaten by the Onça.

https://www.significados.com.br/amigo-da-onca/#:~:text=O%20que%20%C3%A9%20Amigo%20da%20On%C3%A7a%3A&text=A%20origem%20do%20termo%20amigo,se%20para%20todo%20o%20Brasil.