You have never encountered speed until you witness a hypervelocity star escaping a galaxy. In fact, the latest occurrence was the fastest event ever!
US 708 apparently left its galaxy, traveling at over 4 million kilometers an hour (2.7 million mph). The popular belief is that a supernova could be the culprit of this momentum.
Just last year, a multitude of star clusters were expelled by the large galaxy M87 and thought to be related to the black hole. It seems that superfast stars are quite common. The normalcy of these events are the main reason for the collective naming of these heavenly bodies – Hypervelocity Stars (HVS).