Mamajoan captured an altered sign on an MIT door.
Also see this photo from the other Cambridge, in England.
I suspect you may have seen this RT from my Twitter account.
It's worth pointing out that this was posted by @LatymerBiology, which is a school in London.
So I'm pretty sure this sign was seen in That Other Cambridge then. (But it's still funny.)
Thanks, fixed the post.
Similar signs pop up on the doors of the main Cambridge Public Library on Broadway. Better that the signs be made by the Bow and Arrow Press http://www.hcs.harvard.edu/bowarrow/Press/People.html
This is awesome.
But since it's vertical, the halfplane where booze is illegal intersects about half the planet. I predict bootleggers and speakeasies.