I don't particularly like assertions of "all people of binary gender X do Y", but there's a particular kind of don't want to use my brain brattiness that is common in public school-educated teenage boys. Not all of them have it - some are more mature to start with, and it usually improves as they get older. And many of those that do have it don't have it all the time. But I'd rather they were honest with their parents and said "I don't want to have a lesson today" than act like that towards me, because I do, honestly, have better things to do with my life than spend several hours fighting with a child who doesn't want to think. Not because they can't do the work, not because they don't understand the work, but because they're tired & bratty & don't wanna. Yeah, I don't wanna be here either if you're going to behave like that!
And I wouldn't say this is the most frustrating thing in the world, nor is it the most frustrating thing in my life, but it's the most frustrating thing that I come into contact with that could be changed.