Kitten: "And would it kill you to smile?"
Robin: (forcing a "smile") "Maybe."
"This small fae has an almost maniacally friendly grin on its face".
— Pathfinder Bestiary II entry on Brownies
"The expression she produced was technically a smile, but it was one that belonged on something out of deep, dark oceanic depths."
"THAT WAS A SMILE! I SMILED!!"
— Calvin, Calvin and Hobbes
...something flickered around Gryle's thin lips. It was a smile, panicking at finding itself in such an unfamiliar place.
He gave Dorcas and the the bandit a bright smile.
The bandit returned it. At least, he opened his mouth and showed a lot of teeth.
An attractive watchwoman behind him gave him a friendly smile. That was to say, her mouth was turned up at the corners and all her teeth were visible.