This would make a lot more sense if I had a video... please try to hang in there through the explanation!
Signing babies often "babble" with their hands in the same way that speaking ones make those adorable baby noises. My son did it too but now at 2.5 he can usually sign or gesture what he wishes to communicate. On Sunday though I caught him babbling again - and it was so cute!At our current church the services are translated into JSL (Japanese Sign Language) for members who can't hear. In the past month my son has really picked up on the idea of signing as real communication for a whole group of people. One of the main interpreters is also his Sunday School teacher so he's been learning some JSL from her.
The picture here is from a special cemetary service last weekend. That's my son perched on a stone immitating the interpreter. One the surface the difference between ASL (American Sign Language) and JSL may not appear to be much but if you've studied one or the other then they are clearly different languages.
While my son knows they are different he doesn't know enough JSL signs yet to copy what is being said but he has caught on to the basic hand movements enough to babble!
Oh, and he was so proud of himself for being able to babble... :-)