Anyone can be a feminist, it’s not confined to just women. I know many male feminists. It doesn’t emasculate them, or insinuate that that are ‘under the thumb’, all it means is that they are aware that things aren’t necessarily as good for women as they could be.
Benjamin Jones wrote a blog about his stance on feminism a while ago, as well as having posted on other things such as the No More Page 3 campaign (something that I, as a woman, not just a feminist, feel very strongly about).
I recommend everyone toddles on over to his blog to have a read.