Whenever there is a national event like the royal wedding, queensday, a soccer tournament, the elven towns journey or another ice skating event the dutch get the "orange feeling". (Het Oranje gevoel)
People decorate everything, even themselves with orange things of red-white-blue.
Orange is the last name of the royal family; Beatrix of Orange. That's why the people adopted this color to show their feeling of solidarity at special events.
Some pictures of people with the orange feeling at the royal wedding on february 2 you can see here!