Actually, imagining being female doesn't make me uncomfortable at all. As a software developer, it's part of my job to think imaginatively about what someone else might want or not want. How can you manage to develop usable and enjoyable software for someone else if you can't imagine what they'd want - or if you dismiss their desires and preferences? Is it impossible for a male developer to try to imagine the effect of wording or graphics and think, "Hmm, if I were a woman, that might make me feel uncomfortable or talked-down-to; I'd better change that"? I don't think it is.
Have you ever caught yourself saying "nobody would want that" or "nobody would do that"? Quoting Michael Bolton's Rapid Software Testing class, "nobody would do that" means "nobody that I know, and that I like, would do that".
Posting jokes equivalencing software features to large breasts and saying "nobody would really find that offensive" means you're thinking about the entire audience of people as consisting of a group in which someone who would be hurt, upset, or angry doesn't even exist.
I'm no angel. I screw up with this stuff too. But when I see there's a screwup, I try to kindly say, "I think you should seriously consider that what you said is be a screwup." If it was me, then I should say "I screwed up, I have no excuse, and I'm sorry."