Not a very sharp object, with like a pointy object, like the back of a reflex hammer.

不是一个非常尖锐的物体，像一个尖锐的物体，像反射锤的背面。

If you hit my patellar tendon with a reflex hammer, my leg is going to jerk forward, and it's going to jerk forward a lot faster and a lot more predictably than if I had to think about it myself.

如果你用反射锤击打我的髌腱，我的腿就会向前猛拉，而且它会比我自己考虑时更快、更可预测地向前猛拉。