I had a friend who was a bit of a hick and as a subtle dig at him I would greet him by saying "Howdy!" every time I happened to see him. The joke ended up on me as now I almost always greet any stranger by saying "Howdy!" It's like I have no control over it.
I had a boss who was Canadian and he was the first person I recall saying the phrase "Thanks so much." At first blush I thought it was a very pleasing and considerate phrase. Then the more I thought about it the more I had an issue with the phrase. "Thanks so much. Thanks how much? Thanks this much?"
Thing is - even though I now have an issue with the phrase - I still use it reflexively. It's like I have no control over it.