Smile.

to assume a facial expression

 indicating pleasure, favor, or amusement,

 characterized by an upturning of the corners of the mouth.

Here is an excerpt of an actual telephone

 conversation I had last week with a stranger:

S: Yes. I can help you--but first, who is your hero?

Me: Um. Well...It's Kellie.

S: Who?

Me: Kellie.

S: Can you spell that?

Me: K-E-L-L-I-E.

S: Yes. That is correct.

At least I got it right.

Phew.