Judas window
n.— «Classroom surveillance is nothing new. Most classroom doors have a glass section—a Judas window in chalkie parlance—allowing management to surreptitiously spy on Sir’s lesson.» —“Yes, head boys must have the latest toys” by Hugh Reilly Scotsman (Glasgow, Scotland) Mar. 9, 2005. (source: Double-Tongued Dictionary)
Further reading
What if, instead of being an inanimate object, a dictionary were alive? That’s the idea behind a lavishly illustrated new children’s book called The Dictionary Story (Bookshop|Amazon) by Oliver Jeffers and Sam Winston. This is part of a...
Cat hair may be something you brush off, but cat hair is also a slang term that means “money.” In the same way, cat beer isn’t alcoholic — some people use cat beer as a joking term for “milk.” And imagine walking on a...