That awkward moment when you say 'hi' to someone but you aren't sure if they heard you. And then they say 'hi' and you can't decide whether or not you should say hi again in case they didn't hear the first one and you just give them a weird panicked smile.
“And how shall I think of you?' He considered a moment and then laughed. 'Think of me with my nose in a book!” — Susanna Clarke, Jonathan Strange & Mr Norrell