Early in my programming “career”, when I was about 15/16, I started writing network programs in C. I was fascinated by the idea that one program could send and receive data with another far far away. One particular story was a great lesson for me (I eventually ended up naming my company after it), and also pretty amusing. It’s not about undefined behaviour, but about not properly understanding C strings. If you’re curious, the story is here: https://martinrue.com/zzuy-a-lesson-in-perseverance