Setup: an official ping pong ball is floating inside a party plastic cup filled with clean water, which is then dropped from a certain height onto a soft mat.

Observation: the ping pong ball shoots up to a height which is much higher than its initial position.

Question: why does the ping pong ball do that? Why didn't the water and soft mat absorb the kinetic energy? Is this an inelastic collision?
[![enter image description here][1]][1]

PS: the first time it was an accident, the second time the soft mat and I were thrown out XD


  [1]: https://i.sstatic.net/py1vo.png