From the Super Mario Wiki
A Driver Virus is an item in Mario Kart Arcade GP. The Driver Virus's purpose is to attack a player and temporarily slow them down. A driver in possession of the item can release it behind them like a banana peel, possibly hitting another driver. Once afflicted by the Driver Virus, the driver can pass on the virus by coming into contact with other drivers. The Driver Virus resembles Chill with swirling eyes, one of the viruses from Dr. Mario.