Five rupees is all it takes ? 

A week ago I ate at a place and while settling the bill- they were short of 5 rupees. So they gave me a slip that d give me a 5 rupees discount the next time I eat there.

The second incident is when I ate at another restaurant, again the place had to give me 5 rupees. Instead they gave me 10, and asked me to return 5 the next time I go there.

Now, in the first scenario I get 5 rupees if I return and in the second I pay 5 when I return. I’ve not gone back to the first place for a week, but I want to go to the second very soon.

Wonders of trust maybe?