[Certain]

I've only done it once. My girlfriend at the time insisted she wasn't bleeding yet, that tomorrow would be her period and she needed some dick to suffice for the next three or four days.

So I start touching her, mostly to check that my hand wasn't about to come out looking like the prop closet at a horror movie set. She checks out as clean, though.

So I'm going inside her, hitting it missionary because her breasts were her best asset by far. I'm in there for maybe five minutes when we go to switch positions. I pull out for a second, and there's this congealed blob of red right near the tip of my dick and these light-red streaks running down it.

My hard-on disappeared immediately and I shoved her right off me and almost onto the floor. That was about as close as I've ever been to domestic violence, but I wasn't even mad as much as grossed out. I sat in the back corner of the bed for about five minutes, trying to wipe it off with a paper towel. Then I left, went home and took a long shower.

I broke up with her about three weeks later.