It's all about making friends and meeting people

Daisy, her husband and I did dinner last night. On the way back to their place for a tequila aperitif, we ran into their neighbors coming off the elevator: a husband and his very pregnant wife. He was carrying a bag and he matter-of-factly let us know that the city's population was about to be one greater:

"We're on the way to the hospital."

Me, being the smart ass that I am immediately thought of a sarcastic retort. And I was torn between blurting out "Take the epidural and run!!" or "Man, I hope it's yours!"

But I am not a total cretin. I didn't know these people. (And I was having a hard time deciding what to say). Thus, I said nothing.

Daisy, however, said the natural, good-hearted reaction: "Good luck!"

This got us to thinking, when someone tells you this information, what is the appropriate comment?

(I'm looking for suggestions)