Context #1

Tony: Did you take my book?
Jack: What are you talking about? I
didn’t see any book.
Tony: Don’t play dumb. I know you took it.


Context #2

Grace: So did you ask your boyfriend about
that text he got from that girl Chrissy.
Amanda: Yeah, but he played dumb and said that she probably texted the wrong
number.
Grace: So you think he was lying?
Amanda: Yeah, I could tell by the look on his
face.

Meaning: “to play dumb“is used when someone pretends like they
don’t know something, when they really do know!

https://languagesystems.edu/