Looks like this topic has been fairly well discussed already, so I'm just going to echo a couple of people when they say that anal sex definitely shouldn't be used as punishment. Using any type of sex as punishment (be it type, position, method) is just going down a very dangerous road, and if it's not done properly, then...yeah, I think you probably all get the picture. I personally have had little experience in it beyond what I can do myself with a couple of household objects, so take this opinion with a grain of salt.