From the Super Mario Wiki
A Needle Bomb is an offensive item from Mario Kart Arcade GP 2. The Needle Bomb is not a bomb, but a Porcupuffer-like Cheep Cheep. When fired, it travels to its opponent when it is homed correctly. It latches on the opponent and pops two of the opponent's tires on the right side of the kart. The initial strike causes the kart to stop for a brief moment, and, once the the tires are popped, the opponent loses both control and speed. Like all effects, the popped tires eventually recover. Unlike most hazards, if missed, the Needle Bomb lingers in the course until a racer drives into it.