cats

I was once walking down the hallway in my house, and passed my cat going the other direction, and I said "Hi, Zuzu!" and she meowed back, and we kept walking on our separate ways. I thought, "I am now actually communicating with my cat!"

And I was. She was the smartest cat we ever had, and extremely expressive. She even had a sense of humor. She would play jokes and pranks on me to get me to chase her (she liked at least one good chase a day).