I’ve had this happen to me on two occasions. Thought I’d put it out there to see if anyone else had similar experiences.

First time was many years ago with a regular at a popular FS joint in the city. In the shower, things got a little out of hand, pushed the little fella in, it felt super tight, didn’t realize it was the wrong hole till I blew my load and she started washing her backside. Then she told me what we’d done. It felt sensational. (Yes it was bareback - stupid younger me). This was now on offer for all future sessions..

Second time was recently with an ML at a popular place. First time seeing her and asked for Part 3. Initially she was on top, then hopped off to change to doggy. She guided the little fella in and I pushed in all the way. She gasped and collapsed on the table. I realized what I’d done and immediately pulled out and apologized...
She took a few minutes to compose herself, and I was ready to end the session after saying sorry over and over again..
Surprisingly she reached back and guided the little fella into the right hole (without changing doms) and was ready to continue the session like a champion!
Finished up, paid double the tip and left feeling a little strange..

Yes, it probably has to do with my average size and ability to get it rock hard.

Anyone else like to share?