because I was trying to help my wife restrain the other kids and get their devices situated. I fly with some regularity, and so I try to go out of my way to help my wife keep the kids under control out of some semblance of the George Costanza acknowledgement that "we live in a SOCIETY people". But, occasionally I/we miss something. So, my daughter was pushing on the seat, kicking it, etc.
The guy turns to me and says, "hey, is there some reason why your kid is kicking my chair." We haven't taken off yet, and I get it, but I'm not in the mood. I turn slowly over, place my things down, get a little sarcastic with him and ask him if it's "maybe because she's ... 3?" I made it clear I wasn't having any of it and he backs down. I also, of course, do my part to get my daughter's legs under control.
Anyway, stupid confrontation over nothing.
The only thing that really bugs me on a flight is when the parents don't even try, and seem to think we should all just "get it." No, we don't just get it. Most of us have or have had kids, and know that a little effort goes a mile. It's a little stressful, but not usually all that hard.
On the other hand, there are kids that are totally inconsolable, and the vast majority of flyers in those situations are some mixture of annoyed and sorry for the mom, but always more sympathetic if she is at least trying.
Also, headphones.