forbidden fruit
US /fɚˌbɪd.ən ˈfruːt/
UK /fɚˌbɪd.ən ˈfruːt/

1.
fruto proibido
something desired or pleasurable that is not allowed or is illicit
:
•
The secret affair was their forbidden fruit.
O caso secreto era o fruto proibido deles.
•
For some, staying up late feels like a kind of forbidden fruit.
Para alguns, ficar acordado até tarde parece um tipo de fruto proibido.