Classic rock is about heavy hooks, power chords and tight harmonies. But it’s also about letting loose and enjoying the good times. And there’s no better time for that than Friday evening, when we pick up our paycheck, punch out of work and enjoy a couple days of much-needed rest and relaxation.

Good times were in relatively short supply during the weeks leading up to the recording of AC/DC's seventh album, 1980's 'Back in Black.' Although their commercial fortunes were on the rise following the huge international success of their previous release, 1979's 'Highway to Hell,' they were at an emotional crossroads following the stunning death of singer Bon Scott on Feb. 19, 1980.

Considering that 'Back in Black' arrived in stores less than six months after Scott's death, things could have turned out quite a bit differently, but they found the perfect replacement: former Geordie singer Brian Johnson, whom Scott had actually singled out and supported before his passing. Just weeks after taking the gig, Johnson found himself in the Bahamas with his new bandmates, neck-deep in songwriting for what would become AC/DC's greatest commercial triumph.

While a lot of bands would have waited before letting a new member take on such a prominent creative role, guitarist Malcolm Young later told Classic Rock Magazine that the group gave Johnson the assignment of writing lyrics because "He was the new guy and we wanted to make him feel that he was a part of the band. He got straight to it, there was a lot of pressure on him, we had a tight deadline and a producer in [Robert John 'Mutt' Lange] who really tried to make an impact with the vocals, so all eyes were on Brian."

"We'd sit through the night with a couple of bottles of rum with coconut milk in and work. That's where a lot of the lyric ideas came from," laughed Johnson in the same interview. And even though he was quick to accept the lead-singer role in AC/DC, he admitted there was a certain amount of stage fright when it came time to pen those lyrics. As it turned out, it was sitting down to write 'You Shook Me All Night Long' that proved his breakthrough moment.

"I remember sitting in my room writing that and I had this blank sheet of paper and this title, and I was thinking, 'Oh, what have I started?'" Johnson recalled. "And I'll tell you something, and I'm not scared of being called a sissy and I don't believe in spirits and that, but something happened to me that night in that room. Something passed through us, and I felt great about it. I don't give a f-- if people believe me or not, but something washed through me and went 'It's all right, son. It's all right.' This kind of calm. I'd like to think it was Bon, but I can't, because I'm too cynical and I don't want people getting carried away. But something happened, and I just started writing the song."

'You Shook Me All Night Long' was more than all right -- it ended up becoming AC/DC's first U.S. Top 40 hit and the introduction to a record that has gone on to sell a mind-boggling 22 million copies (and counting) over the three-plus decades since its release. It isn't hard to see why 'Shook Me' was so successful as a single, either; from its stomping beat to that tangled solo that begs for air-guitar accompaniment, it's pretty much a perfect rock song.

Johnson shared that sentiment during an interview with USA Weekend, musing, "It was the first song I wrote with the guys, and it has a special groovy beat that won't let you go. It has such a special place in my heart, and I still love to sing it onstage. To me, it might be one of the best rock songs ever written -- if I do say so myself." No arguments here, Mr. Johnson.

Here's hoping all of you get shaken this weekend (in a good way, of course). In fact, why bother waiting for 5 o'clock? Just hit play on that video above, turn up the volume and let the weekend start now.

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