I had an intact, collarless stray show up at my home some years ago. I called the local shelter and got voicemail, so while I was waiting for a call-back I hung out with her and gave her some water and snacks, and lots of petting and scratches. When I scratched her butt it seemed like she flagged a little, so I start caressing under her tail. She seemed okay with it, so I played with her a bit more and then tried mounting her.
I got a lot of rubbing on her vulva, but she would move away when I tried to go in. She seemed excited and kept coming back, and kept letting me rub my dick on her pussy, but no entry. I think she was at the end of her heat. I decided to try fingering her and she stood for that, so after a bit I tried my dick again. It seemed like she may have stood for me after the fingering, but... I was overstimulated at that point; my boner went all rubbery and I couldn't make it work. ?
Kind of like having a torturous cliff-hanger at the end of your favorite TV series, only to find out the series got cancelled. It had been many, many years since I had last been with a canine girl, so it was a major bummer when my cock fizzled out on me right when she seemed willing to let me in. I tried to bring it back to life with her licking me for a bit, but the shelter called and her family was already looking for her so I took her over right away.
Still... I got to finger and rub my dick on some cute girl's puffy muffin for a while! ?
She got safely home to her family later that day. I told the shelter to tell her family she was a beautiful and very friendly dog, and I was glad I got to meet her. ??
I guess that qualifies as my "worst" experience, while still not that bad overall.
Oh, and that I never got a second opportunity to be with the GSD girl I lost my virginity to. She was a friend's dog, so we were around each other a lot, but never the right time or place for another discrete rendezvous.
Oh, and that I think mares are super sexy, but I'm terribly allergic to horses. Like, EpiPen-allergic. ?