That’s Angus out front, making a spectacle of himself as usual, as the soon-to-be-late Bon Scott peers over his shoulder. At left, Malcolm broods in the background.

Today’s birthday is AC/DC lead guitarist Angus Young, born March 31, 1955. That makes Angus 51, and as far as I know, he’s still touring the world in his school uniform with short pants. Well, more power to him. As it were.

Coincidentally, I’ve been listening this week to Highway to Hell, which is pretty much flawless from the opening chords of the title track to the final fadeout of “Night Prowler,” where Bon Scott mutters “Shazbat. Nanu-nanu.” (Anybody born too late to understand what this means: Google “Mork and Mindy.”) Highway to Hell is the best album of its kind ever made, although it’s hard to say what kind that is exactly. AC/DC is a hard band to classify; they’re undoubtedly a rock band, but what kind of rock band? They’re too rhythmically nimble to be heavy metal, too heavy to be pop. Just calling them “hard rock” seems like a cop-out. It might be more accurate to say that AC/DC is a genre unto themselves. If you have High Voltage, Highway, Dirty Deeds Done Dirt Cheap, and maybe Back in Black, you have everything you need in the genre.

While Angus gets all the attention for his flamboyant solos, stage antics, and sartorial sense, AC/DC’s real anchor is brother Malcolm’s rhythm guitar. In the band’s heyday Malcolm Young combined with bassist Cliff Williams and drummer Phil Rudd to form a three-headed rhythm monster rivalled only by Richards/Wyman/Watts or the Who. If you doubt me, just listen to the gut-hammering, surprisingly funky call-and-response riff that powers “Girl’s Got Rhythm.”

And then of course there’s Bon Scott himself, an innovator in the field of “macho guy who sings about sex while shirtless and still kind of sounds like a girl.” Scott left this Earth in 1980, drinking himself into an early grave á la Hank Williams, but not before penning the lyrics to such classics as “Big Balls”:

Some balls are held for charity and some for fancy dress
But when they’re held for pleasure they’re the balls that I like best
My balls are always bouncing to the left and to the right
It’s my belief that my big balls should be held every night

Replacement Brian Johnson took over for Back in Black, which became AC/DC’s best-selling album, and while you’ve got to love songs like “Hell’s Bells” and “Rock’n’Roll Ain’t Noise Pollution,” the band’s been in slow decline ever since. (Then again, who hasn’t?)

So go ahead and raise a toast to Angus tonight, slam one down for Malcolm and the boys, have a moment of morbid introspection in Bon’s honor, then annoy the neighbors with a top-volume midnight airing of “It’s a Long Way to the Top If You Wanna Rock’n’Roll.” You’ll be glad you did, especially once the bagpipes kick in.