Mystery Sign

Like many other parents these days, we've used sign language with Madelyn since she was about six months old. "More, all done, milk, diaper change, home, hungry, water, and please" are all signs that we use on a regular basis. Madelyn understands them all and signs "more, all done, and change" on her own. Of course, it's wonderful that she's learning to communicate in this way (socialization being at least one of our top five goals in raising our children), but I've always felt confident and proud as a mother that regardless of her signs, I generally always understand what she's trying to communicate.

Until recently.

We have a book called "My Friends" that's all about various animals teaching a little girl to run, jump, climb, explore the earth, etc. It's one of Maddie's favorites (she will crawl over to us and literally grab our hand and put the book in our hand to read to her). One of the last pages has a drawing of about a dozen kiddos with outstretched arms that says "I learned to play from my friends at school." EVERY TIME we get to this page, Madelyn enthusiastically pats her tummy with both hands and smiles from little ear to little ear. Friends, I have absolutely NO IDEA what she is saying! Kurt and I have tried and tried to figure it out, and we have come up with nothing. None of the little kiddos in the drawing are patting their tummy, and patting your tummy isn't anywhere close to any of the signs we use. She knows where her tummy is (and her fingers, toes, and nose) and will pat it if we ask "where is your tummy?" but that in no way seems connected to this drawing. It is a complete mystery. And it's just killing us because she seems so genuinely thrilled to show us how emphatically she can pat her tummy each time this page comes up!

Any ideas?