I experienced my first real tank slapper this weekend:
Lessons learned
* Practice in places with no obstacles only
* Don't over-correct or otherwise try to "stop" a skid pre-maturely
* Drift with the roof down to lower the center of gravity
It seems I was "lucky" though. Apparently I only damaged the car's front suspension components. Total repair costs: USD 1,200 incl labor. There was almost no body damage.