"You, person who told me to lighten up, saw one little thing. It didn't seem like a big deal, did it? One little line! One joke! One comment! But it's not just one thing to me: it's one of thousands that I've had to endure since I was old enough to be told that 'X is for boys!' It's probably not even the first thing I've had to deal with that day, unless you've gotten to me pretty early.
That's the main problem with subtle discrimination. It leaves those that it affects the most powerless against it, quietly discouraging them. If they speak up, they're treated to eye rolls at the least, and at the worst, are called oppressors themselves. We're accused of not wanting equal rights, but of wanting tyranny."
Postfeminism is "sex-positive" in the sense that it's all about how awesome it is to be girly and how gross and narsty those annoying feminists are; girls should go wild! according to this kind of postfeminist attitude. If a woman wants to stay home and raise her kids, well, darn it, postfeminism says there's nothing wrong with that, and it's the dirty stupid "you can have it all" feminists who want to kill the American family! Or who want to shame the women who don't aspire to the things that 2nd wave feminism said women should aspire to. If a man makes a joke that degrades women, the postfeminist says "LAUGH AT IT!!! because it's FUNNY!! why are you so sensitive?!?!" The postfeminist is dtf and she's fun as hell...until you criticize her in some way that she thinks is trying to shame her for just being a woman. And then she's not so much fun.
3rd wave feminism isn't so well defined and I don't think that "wave" has quite crested yet. I see you linked to a wiki page on it, but I'd be surprised to see it offering some kind of cohesive definition. In lots of ways, postfeminism wants to be called 3rd wave feminism...but it lacks credibility since it mostly seems geared towards calling female activists bitches and telling them to stfu about gender-based oppression already.
http://en.wikipedia.org/wiki/Sex-positive_movement -- "sex-positive" is a term describing a movement meant to embrace rather than repress sexuality. The play on words of "sex-negative" refers to the opposite of sex-positive, ie., sexual repression.
OP is saying that you are sexually repressed because sex jokes make you uncomfortable. This is a good point, because dongle jokes are actually not "sexist", they are simply sexual. Men hold no exclusive territory over dick jokes, or sex jokes in general. Women can tell dick jokes too. They can also joke about vaginas (Sarah Silverman much?) and both genders can appreciate the humour EQUALLY (yay equality!). Those who don't find it funny are NOT victims of sexism-- they are victims of a shitty sense of humour.
I like sex, I just happen to prefer my work/professional environments without sexual overtones.