Thailand issued the following stamp sometime last year:
Issue 996: National Children’s Day 2013 Commemorative stamps, Issues
This issue commemorates National Children’s Day 2013 (12th January) in Thailand and it is a regular issue each year. This year the stamp features flags and national costumes of the 10 ASEAN member states to raise awareness of the ASEAN Economic Community (AEC)...
And the Brunei stamp showing the Brunei national costumes looked like this: