Last week I got a pinkeye.
So instead of the usual contacts, I had to wear glasses to work.
I get in the elevator. A peer I know quite well walks in, looks at me and proceeds to adopt typical elevator awkwardness behavior (pretending to be focused somewhere else in that one square meter of metal).

Me: Good morning to you too!
Undisclosed clueless peer: Oh! Hi! Sorry, I didn't recognize you!

.....Waaaaa?