when I scratch Luke on the top of his rump right by his tail, he will stick his tongue out and nibble on anything within reach.
Oh man, do I wish we could post videos instead of photos on Pet Talk! I would love to see this! That spot you refer to is what my mom called "the root", where the tail comes off the torso. (She also called it "the root of all evil", because most of our kitties could not stand to be touched there and would turn and bite!)