Reading Caroline Kauffman's interesting article on Impression Management spoke about how people try to leave a certain impression and can sometimes fail horribly. For example, I might think that I look confidant and suave in my three-piece suit and sunglasses but others might think I look stodgy, unfashionable, sexy, or eccentric. It's such a fun source of conflict that people don't use nearly as much as they should. Sit-coms and comedians do it all the time. They understand that the contrast between the impression that a character thinks they leave on people (tough guy) and the actual impression (whiney kid) can be incredibly entertaining.
I had a think about my own novel and realized that there are several entertaining moments (at least I think so) in my story that revolves around this. The most obvious one involves the lad who wants to appear as a dashing gentleman who'd sweep any lady off their feet ... and comes across as a leering adolescent who quotes other people's poetry poorly. There's also the young woman who firmly believes she's coming across as an empathic and friendly companion who can truly understand who people are ... and comes across as an emotionless and creepily overly-analytical ethereal being.
Do you have any characters who leaves a decidedly different first impression than the one they intended? Is it humorous? Or have you managed to do it in a way that's more serious or sinister?