This story just left me speechless in any way and i want to share it. tl;dr at the end.
Im studying computer science in germany and in the first of the small classes i noticed... no, i was disturbed by a guy who would just say that the thing we're learning atm were so easy and the teacher shouldn't even bother to explain it to the class. I don't understand why you would spoile a class that hard... I'm here to learn and listen to the teacher, not to you little asshole. (We were doing basic stuff like binary system etc. but still, let us learn)
So he became unpopular pretty fast.
Fast forward, a few weeks of studying later there was a coding competition where you had to solve different algorithmic problems in a team as fast as possible.
I came there, without a team because my friends aren't interested but I enjoy such tournaments. This guy and me were the only ones without a team and we had to work together.
After him being a total dick for hours i had to watch him code a simple for-loop, that iterates through a sorted array. Nothing special, at this point anyone could do that task in our class so it shouldn't be a problem for him.

He made a simple for-loop and it worked fine, but we figured we had to iterate through the array the other way around.
'Alright', I think. 'Just let the index decr..' 'Pssshhh', he interrupted me and said he knows exactly how to do this.
I was quite impressed when he started to type in 'public int backsort..' in a new line. He tried to resort the array backwards with a quicksort that he then struggled to implement. (Of course we had to implement a quick runtime and we needed that quicksort badly)
I was kind of annoyed but impressed at the same time. I mumbled 'Java has an internal sorting algorithm already' just to amuse myself.
He then used that implementation.
After a few minutes of my pleasure and multiple tests without hitting the requested runtime, i tried to explain to him why we wouldn't need to sort that array backwards and he just couldn't believe it.
I hope that he stays more humble after that..
Also we became last place but thats ok :)

tl;dr: Guy spoiles whole class, brags with his untouchable knowledge (when we do things like binary system). In a competition has to iterate through a sorted array backwards - tries to implement a sorting algorithm to sort it backwards first. I tell him, we could use a already implemented java method. Then tell him we could simply iterate through decreasing the index. Mind-Blown