Leftover Smile

Receiving a smile from someone only because they were previously laughing/smiling at something else. A very embarassing mistake.

I was so happy that he smiled at me, until i realized it was just a leftover smile

leftover smile

The awkward fading smile you have when you stop laughing at someone's joke.

Mike: *tells great joke*
Julia: *laughs, then stops, being left with an awkward leftover smile slowly fading*