Watch John McEnroe play guitar with tennis strings

Based on the lyric content, you may not exactly want to take in a full set of his good-natured singer-songwriter snarl, but even so, John McEnroe recently wielded an acoustic guitar with tennis strings.

Even world No. 1 Novak Djokovic editorializes about McEnroe's voice, offering that "singing is not Johnny's forte."

It came as no stunt. McEnroe and other tennis stars have gone in on the RED campaign to combat Acquired Immune Deficiency Syndrome (AIDS). The instrument, strung with Head-branded strings, has been signed by the likes of Djokovic, Richard Gasquet, Tomas Berdych, Andy Murray, Sloane Stephens, Marin Cilic, Alexander Zverev, Taylor Fritz and (of course) Johnny Mac, a rocker in his own right and married to another, Patti Smyth.

It's up for bids on the RED website (and the auction ends on Monday at 7 p.m. EST).

This group's attempt to help #EndAIDS also includes a racquet bag signed by some of the same people, and you can see the video of a few more (current) tennis stars strumming on those tennis strings as well, from summer.

This isn't the first time tennis and music have come together, and it won't be the last.

Follow Jon on Twitter:@jonscott9