Small jets of fluid

So I had an intense five days and almost six total of being locked up that finished with a splendid edging accident 😊 I am currently at 36 hours caged and already experiencing the same symptom I had during my previous lock up. Whenever I get really aroused and put pressure on myself in the cage, eventually I not only leak fluid but occasionally have little “spurts” where I shoot precum about 4-6 inches out. I guess this is normal? Why does this happen while inside the cage, yet has never occurred when I am loose? Just curious about the science behind it. Thanks