I have experienced sexism at the extreme end of being told by two advisors (one in a summer program, another was my first undergrads advisor) that female undergrads in astronomy are usually just "House-wife Astronomers." i.e., they just get married and leave the field. They both used the same phrase, so apparently it's a common term. The sexism exhibited by my undergraduate advisor was so blatant, it was almost cartoon-like.

But I've also experienced the other more intrusive and icky side of sexism with having a graduate advisor who gave preference to his male students because they were "his buddies" and he no doubt saw himself in them. No matter what they said, they were treated as Brilliant, and no matter what me or his other female grad student said, we were treated like we were Idiots. I learned very quickly to not speak up in his group because any idea that I had got immediately shot down without thought. He is completely unprofessional with his students and has made some pretty sexist comments in the past, although he would never admit that he treats his male & female students differently. It's a lot more nebulous when you're giving "your friends" breaks, and "your friends" happen to only be your male students.

I'm not even going to go into the Nature paper he "gave" to his main male undergrad "buddy". I bitched about that enough in my LJ when it happened.