My first anal orgasm

My first anal orgasm was about the most earth-shattering thing I'd ever experienced. I'd played about a little with rubbing my ass and inserting a finger or two as part of masturbation but I usually stopped and came by jacking off normally. One day I decided to use my then gf's dildo in my ass - I just had an inexplicble urge - so I lubed up and squatted down on the dildo and felt it slide inside me until suddenly I felt a surge of pleasure go right through my cock. I started to slide up and down on the dildo, slowly fucking myself before turning the it on to vibrate - the pleasure flowing from my prostate was fantastic. Instead of sliding up and down the dildo, I just grabbed it with one hand and started fucking my own ass with it and the most intense pleasure built up and built up until I looked down and saw my cock twitch as it shot out a load of thick milky cum! I felt weak and shaken from the intensity of my orgasm and I was so stunned that I'd just come without touching my dick once.