It's really quite simple. A typical programmer is a huge dork who spends three consecutive weekend learning 6502 assembly in his mom's basement so he can write a patch to show Samus naked for the duration of the first Metroid game. Being a male, he has evolved a certain megalomaniacal attitude that makes him think he is super-leet and knows everything about programming, so when the professor is trying to tell everyone how to show that the languages accepted by NFAs are exactly the regular languages, he, knowing that he is already so very smart, spends the time bragging about his latest exploits that nobody really cares about anyway.
Meanwhile, the female programmer in the same university class, is actually listening to the fucking professor. But when lab comes around and she wants to do a search and replace in a pipe, she asks if there's a Unix command for that. The nerd who patched Metroid is sitting next to her and thinks it's awesome that there's a real girl there, and he wants to show off how smart he is so he can get laid for the first time in, well, ever. So he tells her, "Just use sed. Duh. You don't know about sed?" And he makes her feel like a complete retard.
Then she goes to the professor because she's thinking about dropping the class -- because the other people are so obviously smarter than her that they have to tell her such obvious things like what "sed" does.
Of course, the professor is like, "WTF? This woman is like the #2 student and she always aces the tests but she feels like she's an utter moron." Five of the other women in the class didn't talk to the professor and transfer out. Meanwhile the geek's grades slowly drop because he never studies, so that by the time he's a senior he's scraping by, but he graduates with a BS in CS anyway. The behavior of the men in the class degrades further as the fewer women there are in the class, the worse the men are at talking to them.