A new use for spanking

We went to Dallas this evening to have dinner with Chuck's aunt. Somewhere in the middle of our gluten-free meal (yes, I said "gluten-free"), I took Luke to the ladies room at the restaurant. He grudgingly used the ladies room when the men's was locked. We went in and he did his business. I asked him if he was finished. He slapped his bottom and said, "I have to spank the drips out." I couldn't keep the laugh from escaping. I said okay, and he spanked his bottom again. I asked him if he was finished and he said yes and proceeded to pull up his pants. Chuck and I aren't sure whether to be worried or not. Luke, on the other hand, seemed rather amused by the whole thing.