By following the steps on the post, you can get the Mario coin by taking a photo with LEGO Mario at Nintendo NY. And you can get the Luigi coin by taking a photo with LEGO Luigi at LEGO Store 5th Ave.
A YouTube video by KirbyGCN17 shows what the photo area looks like.
But if you want one you’ve got to be quick. They’re only being handed out until the 13th!