It can be because of a habit. I call my female friend "dude" or "man" by accident, and then I realize it and laugh, "oh, wait. You're not a dude!" Then I'll usually make another joke about it.
I always laugh when even girls talk about other girls having balls, and how that's a compliment. Wait. if a woman has balls, then it's not a compliment. if she has guts (even that's silly, all living people have at least some guts in them), then ok.
But "wow, heather, you have balls!" uhhhhhhhh wait; if she does. . . then. . . I don't want to know.
i do it all the time lol. I call everyone dude. my girl friends are just used to it. it just means hey you hey person. I'm not thinking gender just hey you over there who I've known to long to call you by your name. lol that's all
I had a guy friend who called literally EVERYBODY "dude." whether it was me, his best guyfriend, his girlfriend or his mom. (NO JOKE! I guess she was really easygoing lol). So don't be offended by it. To a lot of guys, it's just a habit on the list of habits that they need to break lol.