This bomb was planted planted by Uncle Richard on Tag's own Kart. He planted the bomb there so that Tag would be forced to sign his contract so that Conservative Motors would win the Championship. The plan was a success, as the bomb successfully destroyed Tag's Kart, and the Boom Box with it. It also caused the Chief to be put in a coma due to the explosion.
The contract allowed Richard to claim that he technically won the Crazy Crater race because Tag signed it.