OMG Momoffuzzyfaces! Finally someone else who can do that with their cat! My cat does that too when I get her tickle spot just above the base of her tail. My daughter can get her to do the tongue thing for a long time and it is so funny to watch!
My cat also loves to be scritched behind the ears and under the chin so her head tilts to be scritched better in just the right spots, she will try to scratch with her back leg sometimes too.