In New Super Mario Bros. Wii, there are various mushroom houses that are on the map to get items from.
When completing any level, you will gain an extra mushroom house toward the beginning of the level by touching the flag when the last two digits are paired. The first digit is irrelevant, only the last two count for this.
Gold Mushroom House: Hit the flag when the last two digits are 99
Green Mushroom House: Hit the flag when the last two digits are 11, or 22
Red Mushroom House: Hit the flag when the last two digits are 33, 44, 55, 66, 77, or 88
Note that touching the flag at 00 doesn’t get you anything.
