I have treats in that black box.
Standing silently, I will bow if smiled at or someone says hello.
By asking "what is in the box?" the questioner can then open the box.
Inside are treats: I won't tell you because you'll have to ask me to see when you see me ;)
Some of the items in the box are for sale.
Some are for you to just take.
And SOME require a simple word to receive them: please.
This is the sign for it:
I will ask you to say please in sign. The obligation is for you to say please back. However it is that please is asked in your mother tongue.