pass off as

[dilodi83]

- You're passing me off as a dumb!

Can you suggest me any other verbs or phrasal or expressions to say this?

[JohnParis]

You're making me appear dumb.
You're making me look like a dummy. (casual)

[Alamshar]

A few things with this sentence:

"a dumb" - I think you mean "a dummy" (idiot). In which case the use of "pass off as" doesn't really make sense. If you give me the full context I'll try to help.

"To pass something off" as something else means to fool other people into thinking that it is something that it is not. e.g. "The butcher tried to pass the meat off to me as fresh when I knew it had been in his shop for a week"