“Tank slapper” (TS) is originally a motorcycling term that describes a violent shake of the front wheel that causes the handlebars to slap the sides of the tank. Car drivers have adapted the term to mean an abrupt oversteer and recovery. The motion can be so violent that it flips the car (often with the help of road features but tall cars like SUVs can roll even on a flat surface).
The following clip shows two camera angles of a TS that leads to a frightening incident.
It looks like the oversteer was initiated by a lift throttle oversteer and possibly a slippery berm. FWD cars tend to oversteer having little weight in the rear, so that didn’t help. Ultimately, the countersteer wasn’t big enough or fast enough to prevent the TS and the high berm did rest. Pacific Raceways isn’t high on my bucket list.