something weird happened I need help figuring out what it was

Do to the crazyness of Halloween I didn't have a chance for anal play last weekend so instead I decided to break out my cock and ball rings and a vibrating toy. I put the ring on and placed the toy while on between my legs against my taint. Then I started trying to decide what to watch. During the course of this I started feeling some tingling in my prostate. I was still looking for something to watch whilst the feeling got stronger and stronger. Then after about 10 minutes my cock started twitching and I had what felt like a orgasm but way less intense than normal. This lasted about 7-10 minutes until I grabbed my cock and came normally. I just want to know what it was.