I’ll go first: “You have to have children when you’re young,” told to me when I was in my late 20s, with no desire to ever have kids, and no means to support them, by someone divorced multiple times with at least one adult child who does not speak to them.
Also: Responding to “How do I deal with this problem?” questions with “Oh, don’t worry about it, it’s enough that you’re even thinking about it!”
When I used to make notes because I don’t retain information instantly my boss said “Just don’t forget” I exclaimed: “Thanks, I’m cured!” The office got a laugh but it still bothers me that he thought it was a choice