To those seeing this on their dashboard right now:
If you have Adblock, go to the “Add your own filters” tab and add this to it:
tumblr.com##DIV.stretchy_kidsIt should clear out the ad. It worked for me but if it didn’t for you, let me know.
I am rebloging this on all of my blogs.
Didn’t work for me, I’m afraid. :(