A number of years ago, while on a project in Mexico, we were having lunch in a restaurant, with our partners.
The conversation drifted to currency and I showed Rosy, the person sitting to me, some Canadian coins. I later gave her the coins.
A year later she visited Canada on a speaking tour and gave me seven Mexican coins in friendship, because she said I gave her seven coins.
Now while travelling, I carry seven Canadian coins in a Ziploc bag, with Canadian flag pins and pins from our town.
If I sit next to a person on an aircraft with whom I had a wonderful conversation, I would give them the package with seven coins in friendship from Canada. I might never see the person again.
The last persons I gave the coins were from Cameroon and Pakistan.
This courtesy has grown to about 100 others doing the same, while travelling.