How to drink a bottle of coffee milk after hot spring

This is a very famous etiquette.
How to drink a bottle of coffee milk after you take a bath at a hot spring in Japan.

1) Stand still with your arm akimbo
2) Drink!

I am not joking.
Everybody in Japan knows this...
...and finally, I found the clear instruction on the milk vending machine
at a hot spring in Japan.

Here is the evidence.
It clearly states that it is "a etiquette" with two exclamation marks !!
Don't ask why.
Just follow this instruction when you ever have a chance
to go to a hot spring in Japan
and drink a bottle of milk after you take a bath there.

Everybody would love you!!!

One minor suggestion...
...normal milk is ok,
but try coffee milk or fruit milk if you have choice.
They are the classics ;).

ここまではっきり書かれてるの、初めて見た。
でもなんか、照れくさいよね。思いっきり仁王立ちで、一度やってみたいけど。