How do I respond to this post on my facebook wall?

[Vanessa]

OK so an old guy friend/crush from high school, whom I havent talked to in about a year and miss talking to, just wrote on my facebook wall. All he said was "sniff" It used to be an inside joke type thing we had in our orchestra class. For some reason, whenever he said either the word "sniff" or "baby" it made me start laughing. So from time to time he would randomly say "sniff" "baby" or "babysniff" to make me laugh. It's weird I know. Anywho, I have no idea how to respond to his facebook post! What's something I can say back?!

[Crystal Rayne]

Just say "lol", or something like that, or say, "babysniff", or just tell him you miss those good times.

[Gerardo Griffin]

It means "that's sad" or "I'm sad it's that way." So answer accordingly.