Lots of girls have done that, either openly or secretly.
A reader, anonymous, writes 2 December 2008 : I really don't think its a good idea to ask your brother if you can watch him, yes he probably was thinking about girls when doing it, but not his own sister!! It was a crazy night.
It was so good, we went back for round two.
If my wife likes something he does better than an equivalent thing I do, I want to know what that is, so that I can adapt and please her better.