Weirdly this is the first time I've hearing the term, even though it is something I've practiced for years. Basically I was taught that if you ever really wanted to understand or proof something, teach it to someone else.

Thanks! Now I have a term for it.

Woah thanks for the rubber duck link, that’s fun. But wouldn’t unit tests be even better? You “explain” the code line by line via unit test, except at the end of the exercise you have some tests! I’m only suggesting this because in the past few years I’ve basically discovered this approach to rubber ducking (writing tests when confused/something not working, using said tests to even step through code in a smaller context) and it’s been great.