Worst experience of my teachers?

I had handed in an exercise, which the teacher ostensibly thought was so elegant that he wanted to show it in class. I felt complimented and recognized. But then he proceeded to show the code on the screen, and I objected: "this is not my code, don't give me credit for this piece of shit". It had written-by-said-teacher all over it, because his coding style includes mysterious omnipresent acronyms that you could never guess the meaning of. My peers didn't believe me and thought I had written said not-so-elegant code, and the fuss about it degraded my reputation.

To this day I'm wondering as to why he humiliated me like that. He probably had best intent, but I don't get it