The iconic riff of AC/DC's “Thunderstruck” began as a simple guitar practice exercise. Angus Young was playing around with an acoustic guitar at home when he stumbled upon the distinctive pattern, recorded it on a cassette and later showed it to his brother Malcolm Young. Malcolm immediately heard its potential and encouraged Angus to develop the idea into a song.
The intro is played entirely on the B string, alternating fretted notes with the open string. To achieve the exceptionally clean sound on the recording, Angus taped down all the other strings so they could not ring out, a studio trick he had learned from his older brother George Young. The humble practice lick eventually became the opening hook of “Thunderstruck,” released on AC/DC's 1990 album The Razors Edge.