Mega Mushroom

From MarioWiki

Mega Mushrooms in Mario Party 4 make characters bigger and allow the player to roll two dice blocks from 1-10 and steal 10 coins from other characters that are passed in the duration of the turn. However, the user is also forced to skip board events, like buying items or stars. In New Super Mario Bros. for the Nintendo DS, Mega Mushrooms cause Mario or Luigi to grow to the size of the entire screen for a limited amount of time, destroying anything in their path including warp pipes, enemies, blocks, and even the end-level flagpoles. It also allows the player to kill a boss by walking into him. The megameter is featured at the top of the screen and is filled up by destroying the various objects. When the effect ends, 1-Up Mushrooms are awarded based on the portion of the meter that has been filled. If the meter is completely full, the player is awarded five 1-Up Mushrooms. The Mega Mushroom has the same color scheme of the original Super Mushroom from Super Mario Bros..

Mega Mushrooms are also present in Super Mario 64 DS, where they look more like traditional Super Mushrooms, but make the player much larger and able to destroy some otherwise indestructable obstacles and enemies, such as Thwomps, most pipes and bosses.

They also appear in Mario Kart Wii. They share their usual purpose here by increase the player's size dramatically. Here it gives them a boost in speed, like the starman, and the ability to crush opponents, making them slow down.