There are some English phrases that I had apparently been oblivious too (or just hadn't noticed) until a certain point and thought they're a little weird (and I am a native English speaker).. Maybe these might seem nitpicky, but here's my list: Rucksack: I had never heard this word until I was studying German in high school. Rucksack is the German word for backpack. Then I started noticing people using "rucksack" in English speech & written things. I thought it was odd since we have the English word "backpack", and I've wondered why use a foreign-language word when English has a word for it? The use of "an" before words starting with H. I hadn't noticed or heard of that rule until I was around 19 or so. Using dots to separate elements of a date (such as 2020.04.17) or a phone number. For a date, I had always seen people use slashes or dashes, and for a phone number, I had always seen dashes (and sometimes the area code in parenthesis). I started noticing people using dots separating those things maybe 10ish years ago? People saying numbers for months when speaking dates (such as "four seventeen 2020" for April 17, 2020) - I started noticing this also about 10ish years ago, and it sounds weird to me to hear a number spoken in place of a month name. Is there anything you never noticed people say or write until some point later in your life?