go as

go as (someone or something)

To attend a party or other social gathering in costume or dressed up to resemble someone or something. I'm going as Marilyn Monroe—how about you? A: "We should go as fairies!" B: "Yes! I already have a pair of sparkly wings from an old Halloween costume."
See also: go
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

go as someone or something

to pretend to be someone or a type of person. There's a costume party this weekend. I'm going as Santa Claus. My husband and I are going as a king and queen.
See also: go
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
See also:
References in classic literature ?
"I think it was so splendid in Father to go as chaplain when he was too old to be drafted, and not strong enough for a soldier," said Meg warmly.
"Don't I wish I could go as a drummer, a vivan--what's its name?