Our cat, Stewie, will answer us anytime we say his name and the word "What??". No matter where he is in the house, if he hears someone say "What?" we'll hear him meow in response. He'll also do it over and over and over again...
"Stewie, what??"
"Meow!"
"Good Kitty. What?"
"Meow!"
"What??"
"Meow!"
It's hysterical! He often has other conversations with us when he's in the mood to "talk", too.