The Likable Shithead

Sometimes in life you run across an individual who you like, except that they are a shithead. Every once in a while, that individual is a student. You find yourself asking why am I bothering trying to help this kid? They screw up royally; and when you call them on it, a twinkle develops in their eye, and their cheek involuntarily raises the corner of their mouth. They know better. And they know you'll fall for it every time.
When did this kid gain control like this? Why is this kid controlling everything? You are confused. You want to not like the student, but, uh, that wry smile gets you. You like their spunk, their stubborness. You go to your colleagues, and all you can say is, That kid is a shithead, but a likable one.