From a Tumblr spokesperson:
There is a viral post circulating on Tumblr which begins “Dearest ‘Tumblr’ users”. If you have viewed this post, please log out of all browsers that may be using Tumblr immediately. Our engineers are working to resolve the issue as swiftly as possible. Thank you.
Tumblrs to avoid at the moment: Daily Dot, CNET, The Verge.
So is this why everything’s all weird and wonky?
ETA: According to the Guardian, Entertainment Weekly and USA Today have been hit as well.
Son of ETA: Tumblr says it’s been resolved. \o/