Judah and Micheal are watching Signing Time and when the "Silly Pizza Song" came on, Judah signed CHEESE. Hoorah!

Although he did his own interpretation of AIRPLANE a few weeks ago, the only other sign he has been doing is some thing that I can't find in the ASL dictionary where he puts his thumb and index finger in a pinch and taps the palm of his left hand with them. He does it everytime the video is on and also when we play with his toys but I can't figure out a) how he learned it or b) what it means.