Unless you have taught highschool algebra in Iran, you could not make sense of the phrase: Elephant and Teacup Identity! This is what teachers use to refer to the following identities:
$ (a+b)(a^2-ab+b^2)=a^3+b^3$ and $ (a-b)(a^2+ab+b^2)=a^3-b^3$
Such reference is so common that today a colleague of mine (in a discussion about students' algebraic difficulty) referred to it assuming that I know what she is referring to. Whether or not such references would be of any help to students is an important question, but not my question now. For this post, the question is:
Do you know any of these linguistic references for communicating mathematics? It could be something that you use in your own class, or you have heard that someone else uses. Thus, it doesn't matter whether its usage is limited to just one class, or is as popular as the one I gave.
Edit. The first attempt to clarify the question. The question is looking for "non-mathematical" terms or phrases that are used to refer to mathematical objects (of any kind) mainly for educational purposes.
Edit. The second attempt to clarify the question. Admittedly the question is a bit vague. Do examples like "continuity", "saddle point", "horseshoe map", or "hairy ball theorem" count? I guess not. They are now formal terms belonging to Mathematics culture here, there and everywhere. What if we call what this question is looking for "mathematical slang". Here is a dictionary definition of slang:
A type of language consisting of words and phrases that are regarded as very informal, are more common in speech than writing, and are typically restricted to a particular context or group of people.
Interesting, after coming with the term, I found this paper "The blight of mathematical slang", that gives the expression "cross-multiply" as an example.
Edit. Following a number of suggestions for using a more informative title (see comments below), I changed it in a way that also better reflects the final version of the question (previous edit).