[T.B. Yoits]

"I'm not a doctor but I play one on TV."

"He's not a manager/director/executive/etc but he plays one on TV."

(Yes, it's from a television commercial but it's common in workplaces when someone's sitting in a role but has no clue how to do the job and so might as well be an actor).

[T.B. Yoits]

“...so preoccupied with whether or not they could, they didn’t stop to think if they should.”

[T.B. Yoits]

They're all going to laugh at you.