Q:

Etymology of "rinse and repeat"

I've noticed that people love to use the phrase rinse and repeat.
Where exactly did it come from?

A:

It could have some sort of origin in the advertising of shampoo:

Lather, rinse, repeat is a phrase that is a common part of the instructions on shampoo bottles. It is sometimes also used as a humorous way of saying that a certain set of instructions should be repeated until an explicit or implicit goal is reached, or as sardonic commentary on some people's practice of taking descriptions, instructions or expressions literally and without common sense. Often the phrase is shortened to simply "Rinse and repeat".

As you can see, the phrase has been used out of context, so that instead of just referring to shampoo, it can be used for anything now.

