Who can find it?

I know a couple of you have already seen this, but for the rest: Can you find the inappropriate action being made by my precious Josh?
I am going to have to have a discussion with him. Maybe it will be much shorter than I think it will. Maybe he knows what it means and just needs to know that doing that in public is NOT okay. Not the actual ACT but the thing with the fingers and the tongue-hah!
I decided I'll ask him if he knows what it means. If he doesn't- how much do I tell him? He's SEVEN.
HELP!