First go to edit game type and create a new game with all the vehicles on and the suicide penelty set at it's maximum (15 Seconds). Now you can do this three ways: Wait until your opponent is going to or around the vehicle (Prefebly The Warthog) then go to the opposite side and throw a PLASMA grenade on it and if you aimed right, the vehicle will topple your opponent and count as a suicide thus giving you 15 seconds to think about your next plot!