As for the image of a dog chasing its own tail, it's based on BBC's reporting of the situation. The site posted a statement on Twitter in the early morning hours saying it was "aware of a technical issue" affecting its website, but declined to elaborate. A BBC News journalist for the site's Technology section posted an article saying that internal sources blamed the issues on a DDoS attack, then a few paragraphs down notes that "BBC has yet to confirm or deny that such an attack was responsible for the problems."
So there you have it -- BBC acknowledged a technical issue (duh) while one of its own journalists heard from people within the organization that it was a DDoS attack, but for some unknown reason the site won't go on record as saying so.
Take the lack of information and combine it with how long it took the site to restore operations and you have sufficient cause for humorous Twitter posts like this one:
And this one: