Definition
Used to describe someone who is very astute and not easily deceived or tricked.
不容易受騙
Don't try to trick him; there are no flies on him.
別想騙他；他可不是好糊弄的。
She has been in the business for years, and there are no flies on her.
她在這行已經多年，非常精明。
In business negotiations, you have to be alert because there are no flies on the other party.
在商業談判中，你必須保持警覺，因為對方非常精明。