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

1.
禁果
something desired or pleasurable that is not allowed or is illicit
:
•
The secret affair was their forbidden fruit.
那段秘密恋情是他们的禁果。
•
For some, staying up late feels like a kind of forbidden fruit.
对一些人来说,熬夜就像一种禁果。