You've got to appreciate the irony: Randi Zuckerberg, sister of Mark and a former director of Facebook, is all of a twitter over what she sees as a breach of privacy.
She'd posted a picture on Facebook of her and her family laughing at a new mobile app called Poke. However, one of her friends' friends - Vox Media marketing director Callie Schweitzer - saw the picture and reposted it to Twitter, assuming it was meant for public consumption.
Zuckerberg is outraged by what's happened, describing it as 'way uncool'.
"Digital etiquette: always ask permission before posting a friend's photo publicly. It's not about privacy settings, it's about human decency," she complains on Twitter.
But the irony hasn't been lost on some of her followers.
"Instead of vilifying a subscriber for not reading your mind, maybe you should talk to your brother about recent FB changes," suggested one. "It sucks that she's blaming this on the subscriber's "etiquette," and not her own confusion about her bro's privacy settings."
"Nice attempt at spinning #facebook's failures w/ privacy settings to a failure in human decency," added another.
Schweitzer was able to see the picture because she's friends with one of the people tagged in it, another Zuckerberg family member, and found the picture at the top of her news feed. Nevertheless, she's apologized repeatedly on Twitter to Randi Zuckerberg.
She's deleted the photo - but rather too late, as it's since been picked up and republished far and wide.