Entering a shop
Quicky: long overdue, but here goes anyway. So, when you enter a shop or restaurant, be prepared to be shouted at by as many employees that you can or cannot see. They will cry out irasshaimase at you, indicating that you are very welcome in their shop (and in doing so, possibly, alerting colleagues).
Read more, here.
And also, this is very, very true as by personal experience.