It’s probably not cool to admit that I googled the meaning of this little hand gesture that you and your Daddy do, but I did because I have to keep up with you! And now I know. It’s the shaka sign which is a gesture of greeting. It is associated with Hawaii and surfers (also other boarding sports like Skateboarding and Snowboarding). The instructions were quite explicit. You extend your thumb and pinky finger while keeping the three middle fingers curled. You then raise your hand in salutation with your fingers facing you. Apparently, for emphasis, you can wiggle your hand back and forth. Some of the many meanings of the shaka hand sign are hello, goodbye, cool, okay, see you later and take care.
So now I know although I’m sure you’ll also have your very own interpretation of it!