Is it normal to fantasize about having oral sex with your best friend?

I'm a straight girl by the way and recently I've been having the urge to have oral sex with my best friend. She's straight too. I've never ever been attracted to a girl and I don't think I'm attracted to her i just get sexual impulses. She's definitely more open about her sexual experiences than me - so I think they may play a part in this, but wat do u think? I'm confused!