Other People's Kids.
Let me start by stating that this only goes for strangers' kids. Not for the kids of friends and family. I like those kids. :)
I've always been fond of children. One of my earliest memories is of seeing a small toddler, and thinking, "Aww. I love kids." And then realizing that was an incredibly odd thought for a five-year-old. By the end of Kindergarten, I knew I wanted to teach, and by the time I was 12, I was telling my grandmother that I wanted to be a "professional mommy".* Later, I got my degree in education, and worked my way through school at daycares, schools, and as a nanny. And I loved those kids. Every one of them.
And then I had my own kid. And he is awesome.
Suddenly, other people's kids lost their luster.
I found myself becoming annoyed with children for the first time ever. That kid being a little jerk in the store? Suddenly, I was just glad he wasn't mine (at least, not this time). That cute newborn at a restaurant? For the first time, I had zero desire to coo over it. The adorable little girl dancing at Faire? Cute. Meh.
It's not that I hate OPKs, or even really dislike them. I'm just not interested in them. Not in the least.
I have my own, now. And he's plenty interesting and cute all on his own. :)
*How prophetic of 12-year-old me. . .