Don't even look like

Don't even look like (something!)

Do not even appear to be doing something! (The something can be thinking about something or actually doing something.) Mary: Are you thinking about taking that last piece of cake? Bob: Of course not. Mary: Well, don't even look like you're doing it! John: You weren't going to try to sneak into the theater, were you? Bob: No. John: Well, don't even look like it, if you know what's good for you.
See also: even, like, look