If Charlie Sheen is your bro, rest assured he ALWAYS has your back. Case in point: this John Mayer fake Rolex mess. What does Sheen have to do with it and why is he firing insults at Mayer and his music via Twitter? Sit back and we'll tell you.

Mayer, a watch collector, recently filed a lawsuit against Robert Maron, a watch dealer and a friend of Sheen, who is also a watch collector. According to TMZ, Mayer claims that Maron sold him counterfeit timepieces -- to the tune of $5 million -- a few years back when he was seeking vintage Rolexes.

Legal papers suggest that seven pieces that Maron sold to Mayer were fake and their inauthenticity was confirmed by Rolex after Mayer sent one out for repair. Mayer is seeking a refund of $656,000.

On the flip, Maron's people say that Mayer was aware that he was receiving faux items and that he even posted that he wanted the Flat Dial model, despite having fake parts, on a Rolex message board back in 2007.

What a mess, right?

Well, Sheen leapt to Maron's defense in a tweet, where he simultaneously took down Mayer's music, calling it "milk toast girlie drivel he calls muzak."

Ouch! Yeah, he went there.

At least Maron can rest assured that C. Sheen has his back. Will Katy Perry jump to her ex's defense?

Below is Sheen's mean tweet. It's sad that he and Mayer can't get along. Both have a penchant for dating extremely hot women.