You know how sometimes we say something sarcastically, and do the double-finger twitch that's supposed to symbolize quotation marks? How do you write that in non-dialogue text (narration)? Not describing that a character is talking like that and doing those things with his fingers, but as part of the non-dialog text.
He gave him a "playful" look.
(Would this be correct?)
P.S. Please don't tell me to describe what the character's eyes looked like (showing not telling). I know that already. This is just an example. I'm asking what I (the writer/narrator) could do to express sarcasm in the text.