「let's」は誰かと一緒にしたいことを表わす。

First, I have to admit that the headline of this post might be really broken Japanese. I'm not quite sure how to say that. Someone please email me a better version!

• broken English
  片言英語 (definition from Eijiro on the Web)
  

What I want to say is that "let's" expresses something that you want to do together with someone else. I've talked about that before on this blog:

http://upgradeenglish.blogspot.com/2009/04/dont-use-lets-if-you-are-giving-someone.html
http://upgradeenglish.blogspot.com/2009/09/blog-post.html

I was eating at a nice vegetarian restaurant in Bangkok where I also saw this mistake. Now I know it's not a mistake which is only found in Japan. The sign reads:

× Let's wash your hands <- "let's" is wrong, and there's no period either.
○ Please wash your hands.

I wonder if it would be nice for someone to help me wash my hands. After all, at a salon, people wash your hair. When you get a foot massage, the masseur washes your feet.

• マッサージ師 (マッサージし) (n) masseuse; masseur;

However, no one has ever helped me to wash my hands, at least not in the past 30 years, I think.

Anyway, everywhere people are worried about the flu, and at least washing hands is a better defense than wearing a mask.

Let's help each other to learn new languages. I've written this post, so now somebody check my headline for me, please!