Thunder Cloud

The Thunder Cloud (also called Lightning Cloud) is an item from the Mario Kart series, appearing in Mario Kart Arcade GP, Mario Kart Arcade GP 2 and Mario Kart Wii. Unlike other items, it activates itself automatically when obtained from an Item Box, so players can't exploit it and activate it and immediately bump someone.

When obtained, the player automatically receives a boost of speed, constantly. However, the Thunder Cloud will eventually strike Lightning at the player, shrinking them. The Cloud however can be passed on to another kart by bumping into any other racer before the lightning strikes. To use the item efficiently, racers will have to bump another player and let him/her be shrunk instead, while still having kept it long enough to fully benefit from the speed boost it gives. The music on the race track will be sped up if a user-controlled player gets hit from it.

Trivia

 * Thunder Cloud gives the player the same speed as a Star.
 * Lakithunder, a boss in New Super Mario Bros. rides what appears to be a Thunder Cloud.