On 7 days from Sunday to Saturday, there are 7 different colors. For instance, Monday is considered as yellow. King Bhumibol was born on Monday, that is why his flag is yellow. People wearing yellow t-shirts to honor him. Friday is regarded as blue. Queen Sirikit was born on Friday. Her royal flag is obviously blue. Definitely, many people wearing blue t-shirts to show respect to her majesty. Seven days also relate to seven different postures of birthday Buddha statues which have seven different meanings.