My girlfriend doesn't use anything besides her body on me, but I'd say that I'd be down for just about anything with her. It's all fun and games. I don't see any reason not to except for some personal limits based on insecurities (not trying to attack anyone here....) . It's not only unharmful to both partners, but it also feels amazing. Still, the only problem I can think of would be the breaking down of controll on the man's side who might be used to having the 'upper hand'
Simply saying that you don't like things up your ass is a pretty hasty conclusion seeing that most guys are yet to even try it. To each their own though, but I tend to choose 'pleasure' whenever I can
