Whereby someone posts an AIBU thread and another poster comes along with a tenuously-linked scenario in which they are clearly not being in any way unreasonable and proceeds to get very offended, indignant and self-righteous.
For example:
OP: AIBU to think you shouldn't buy a pet if you are not able to look after it?
Outraged Poster: Well we bought a dog to have as a family pet and we loved it very much, but then my husband had a freak accident at work and all his fingers and toes fell off, and my DS developed a life-threatening allergy to dogs and then my MIL, my best friend, my next-door neighbour and my beautician passed away, and I was diagnosed with acute housemaid's knee in both knees so I couldn't walk more than half a dozen paces, but if you want to judge us for not coping and for asking my sister to look after DDog for two weeks while I recovered then you go right ahead!
Or something to that effect...