Snap oversteer is the propensity of a vehicle to spin dramatically during a turn (usually unexpectedly).
Causes
This is most common with mid-mounted engine, rear wheel drive (MR) vehicles. Mid-mounted engine vehicles have a much lower rotational inertia than vehicles with a front-mounted or rear-mounted engine. The lower rotational inertia of mid-mounted engine vehicles causes the vehicle to spin much faster than a front or rear mounted engine vehicle. If unexpected it can catch the driver off guard when cornering, ultimately leading to loss of control of the vehicle.
Snap oversteer is induced when the throttle is lifted while mid-way through a corner (lift-off oversteer), often by inexperienced drivers trying to reduce speed after braking too little.