My partner and I were ramping up to anal. He had just very thoroughly lubed himself and me with silicone lube. Before we started this we were having PIV. I'm kinda side laying, prone bone which is a position we use a lot especially for the initial penetration. He penetrated me partially and either slipped out or he pulled out to reposition, not really important, don't really remember. He tries to go back in and in about a millisecond before I could even reach down or say anything he slid right into my vagina. He immediately pulled out. It was definitely an accident. The combo of being so slick from the lube and having just stopped PIV I think meant I was just more ahem, open which made it easier for this to happen. I should mention that this was not a planned anal session and I did not clean out ahead of time. To be clear, there was no mess but there were probably more germs present than usual given that. We did not have gentle PIV (totally consensual!!!) and there was irritation from that. It ended about as well as you're imagining. Don't worry I have antifungals and probiotics on board. I'm just kinda horrified by it and also think its a little amusing in an awful sort of way. I haven't told him what happened yet and I just needed to tell people who could be horrified and amused with me lol.