Aside from a few predictable hiccups, Twitter’s new video app, Vine, was enjoying a successful launch. Users were hopping aboard en masse, brands were experimenting with the service, verified accounts were emerging, and all was well – until today when very many users found explicit pornography in their video feeds.

How did it happen? Well, since Vine isn’t really fun unless you follow a lot of people – and the service is still brand new – the app automatically includes “Editor’s Picks” in every users’ feed. Generally, they’re amusing, involve food and/or smiling faces. However, today the app, which auto-plays videos as you scroll past, accidentally included an explicit post by user NSWFVine. in case you don’t know, NSFW stands for ‘Not Safe For Work’.

Twitter is currently blaming the mistake on “human error”, though it hasn’t confirmed whether or not the “error” was made by human or machine.

(More on this story – and some NSFW language – at BuzzFeed)