Hmm, I would think that your friends are a little close-minded, like other people said, and maybe they haven't been exposed to much. I don't have sex on my period because my boyfriend thinks it's gross. So do I to a certain extent, but if I really want sex, I could care less. Also, I don't let my boyfriend orgasm in my mouth because 1) I'm not sure how it'll taste and 2) there's something about it that seems a little...scandalous, lol. BUT that's just for me. I don't look down on other girls who do it and sometime I wish I could, but I can't! It awesome that other people can be so sexually open and limitless.