What does it mean when a guy calls a girl "dude"?

Anonymous
So there's this guy I kind of like; we have some classes together at college. I have an inkling that he likes me but I've been confused because one of his friends that he always hangs out with is a girl and before I knew them, it seemed like they were probably together. Come to find out, they're not; so I assumed they liked each other because they're always hanging out together.
But then a few weeks back he asked if I had a boyfriend (he thought I was dating a friend of mine, I'm not) and then just today I was eating lunch with him and his friend and he called her "dude." I don't know about you, but it doesn't seem likely to me that a guy would call a girl they liked/wanted to date, "dude." Side note: he's never called me that.
So what do you think girls? Guys, if you liked a girl would you call her dude?
What does it mean when a guy calls a girl "dude"?
9 Opinion