I was with this one-night-stand lady, and she was a single mom ditched by her husband when he found out she was pregnant. She told me her story. When young, she had an accident involving penetration of her vagina by a mechanical ob
ject (a true accident, in a bus). After she was hospitalized the doctors told her that she might have lost her fertility. So when she got married she decided to test her ability to conceive. But her husband was not ready. So she doctored his condoms, and pretty quickly she fell pregnant. The husband, however, was not happy with this result and divorced her. (I don't know, perhaps he suspected the doctoring, perhaps he suspected it was someone else's baby.) That was the first time the idea to sabotage a condom came to my head. I have never met anyone else in person who admitted to such a thing.