I recently saw one doing this. It was a different design where I think it was meant to look like it’s waving at the elbow, but much of the time, the “bicep” part deflated and the arm dropped, then to get into the wave position again, would come out the front of the body.

To translate the arm movement, it was like, “Hello! Hello! Hello!.. Heil! Hello! Hello!.. Heil!”