Very sad. AC/DC was the very first rock band I was ever interested in in my life. Before I was introduced to them by my cousin and my brother, I was a budding MC Hammer fan. The first AC/DC song I ever heard was Thunderstruck, and it changed my life forever. From then on, my taste in music was all about in your face hard rock/heavy metal guitar.
Since OP already posted Thunderstruck, I'll post Hells Bells. When I was a budding guitar newbie at the age of 13, I wasn't really having much fun with it until I found tablature on the Internet and learned the intro to Hells Bells. I was amazed that I learned some AC/DC and it made playing guitar fun for the first time. I would then spend my entire adolescence and early 20s playing guitar every day as a great hobby. Since last year I've been getting into it again and am now in a real band for the first time in my life.
Thank you, Malcolm Young and AC/DC! \m/