Here is a quick list of things that never occurred to me for decades, even though I'd heard of most of these words since childhood or young adulthood, at least. The last one is new to me (say, the past couple of years, at the outside).
1. SUGAR. Why is it not spelled 'shugar'? In French the word is 'sucre', and yes, the first two letters are spelt how they sound or sound how they're spelt: like the first part of 'Susan'. Why in English do we put an H there?
2. Robert The Bruce. Was this Scottish king Robert Bruce? What is 'a Bruce', never mind 'THE Bruce'? Are we to imagine this? -- There was only one Bruce, or The Bruce, in the world, and Robert was it. Apparently 'the' is an Anglophone representation of 'de', commonly used by French people and by those ghastly Normans that conquered England. Though why Robert wasn't therefore Robert de Bruce remains a mystery: no Robert de Vere, Earl of Oxford (there was more than one) styled himself Robert the Vere that I know of.
3. 'You're welcome'. I've never liked this expression. If someone thanks me, I respond with 'my pleasure': it's much more gracious, in my opinion. 'Welcome' means that something's presence is appreciated and perhaps expected. What does that have to do with courteously acknowledging someone else's gratitude?
4. 'Bucket list'. If such a list is meant to include the important things you wish to do in life, where does a bucket come into it? As a gardener I use buckets for dirt, pulled-up roots, new soil, and water. I can't imagine describing any long-cherished goals as belonging in, or being carried in, a bucket. 'Wish pot', if one needs a term, makes far more sense.