Seen in Hong Kong:

A nice little visual aid to remind travellers to dispose of their water bottles here in the garbage can (the arrow does point in the right direction; I took the liberty of rotating the lineup for the picture).

This takes for granted that travellers understand English, Chinese and/or common security restrictions. How might you understand this setup if you didn’t know one of those things? Here’s one possibility (on the same table as the bottles, but from the other side):

Perhaps he thought the disposal was for recycling plastic water bottles. Or maybe not.