Disney Epic Mickey 2: The Power of Two

On you're way in the first mission (Yen Sid's Lab) there is at a certain point a box that's half hidden in the wall and you get the choice to paint or thin it. If you thin it you will get 100 'dollars' and when you choose to paint it the box can be opened and you will get you're first pin. So just paint the wall/box woth RT, grap the pin and the achievement is yours.

Sorry for my English. I'm Dutch and wasn't the best in school ;)