Here is a pair of pins that were sold/given away together. They are uncommon enamel & metal pins. Sonic is shown with a soccer football, and Japanese styled classic Tails is standing in front of a flag. But which country has that flag? Is it Ethiopia? (color looks a bit off, is it red/yellow/green or orange/yellow/green?) It could be that the pin faded or yellowed over time. This was apparently released with Sonic Spinball in Japan. It could have been a bonus or pre-order item. It was clearly shown in a commercial.

Ethiopia is a country in Africa that has a lot of problems for a long time. It is highly unlikely that they made any sort of pin due to the struggle of the country.So why would Japan make an Ethiopia flag pin for itself? This makes the mystery even more strange. Ethiopia flag data by: Encas

You can see the pins being advertised at about 2:58 in this commercial video compilation: Japanese Sonic Game Ads, at youtube. Commercial info by: AskLiliumLily

In case the youtube link will ever be removed, below you can watch it from the Sonic District video archive: