MEME REFERENCE

What's on your mind?

Use to reveal the one thought, obsession, worry, or oddly specific subject occupying someone's mind beneath a calm exterior.

What it expresses: An outwardly ordinary person is contrasted with the dominant idea inside their head.
Example: During dinner you keep thinking about whether you locked the office, so you label the skull with that intrusive concern.
When not to use it: A friend openly tells everyone exactly what they are considering; there is no hidden inner thought to expose.