I’ve seen a surge of kitty threads lately and thought I’d throw another into the mix. In all the years I’ve owned cats, I’ve never had one that does this before.
Maybe he’s trying out for a position as an emoticon. 
Mine will do that sometimes if interrupted mid-groom. It’s adorable, and so is your kitty. (Name?)
All mine do that sometimes but one does it ALL the time! Of course it might be that it’s because she has no fangs and thus there’s nothing to hold her tongue in. I prefer to think that she knows how squeezably adorable this makes her. She’s a manipulative little devil.
Hahaha - great picture! I’ve never seen any of mine do that.
Woops, thought I’d put it in there. His name is Storm and he quite often lives up to it.
I read somewhere that cats have no nerve endings in their tongues, so if for some reason the cat gets interrupted in mid-wash, it will forget to retrieve the equipment.
I had a cat that did that frequently. I would move up close to her and gently grasp the tip of the tongue in my fingers. She would start to pull her head back and get the most startled look on her face. Priceless!