And yes, sadly this is relevant, because, as much as we all have the right to decide when we are offended and not, there will always be people, consciously or not, who will game the system.
And you aren't offended by people who walk slowly in front of you - you are annoyed.
Similarly, in this context, I'd disagree: No, saying "dongle" in earshot of someone who tweets about "enhancing" the contents of one's shorts by stuffing socks down them does not give the over-hearer any "right" to be offend-ED, since it obviously isn't anything that this worthy regards as particularly offens-IVE. She obviously claimed the right to _maintain_ that she was offended, but by any sensible definition of the word she actually wasn't.
[Edit:] Duh, that's what I get for replying in a browser tab I opened ages ago -- I see someone said most of that already.
She published this joke about sexual humiliation from the same conference:
https://twitter.com/adriarichards/status/312265091791847425
And the company she was envangelising for on that twitter feed thinks that a visual joke about photocopying your genitals is not inappropriate for their jobs pages:
http://i.imgur.com/uWc8P39.png
I understand that speaker and context make all the difference, but she made a joke about sexual humiliation to thousands, and then, at the same conference, got offended by overhearing joke conflating dongles to genitals.
I agree with you that resorting to sexual slurs is immensely counterproductive and makes one look stupid, but I can also understand why angry people would reach for them, since this is in the line of the discussion. Understand, but not excuse.
Still the point stays - you don't make penis jokes and then get offended by penis jokes.