Where is Curly?

During a meeting today, the host was asking who joined the conference call...

host: "Hello, who just joined the call?"
person A: "this is Larry"   (Larry Hirsch, an engineering lab manager)
person B: "this is Mo"   (Mohamed Rezvani, a program manager)
....
....
....
After the roll call was done, a colleague suddenly commented:

"Where is Curly?"

Almost everyone in the room started laughing.  I didn't get it.  Then someone explained to me that this is a reference to the 3 Stooges show, and this coincidence made the perfect setting for the joke.

The 3 characters from left to right: Moe Howard, Curly Howard, and Larry Fine.