To thank or not to thank

Last night at bowling I had to change. I wore a skirt to work so I brought a pair of jeans. As I was leaving the bathroom, some old man standing by the lockers to get his bowling shoes says in his gruff old voice..."you looked better in a dress". I wasn't sure if I was supposed to thank him.
Later on, I was speaking to a teammate of mine. He was sitting down and I was standing facing him. Out of the blue somebody slapped my ass. I assumed it was one of my other teammates, but I still found it pretty odd. I don't really know them that well and I didn't think either of them would do something like that. Well I turned around only to find it was another girl in the league. And she said with authority "wow, you have a really nice firm behind". I wasn't sure if I was supposed to thank her.
Thanks? or no thanks?