We have been teaching Buttercup the 1st part of his new name; Butter. I redeveloped this little song (Rubber Ducky) and sing it to him often. Today when I was eating breakfast, I was singing it to him and he spontaneously started doing the wave, in time, to the song. Then he started making a growling sound like he was singing with me. Well, I tried to recreate it...never as good but he does do the wave without being told.