Based on various interviews with the people involved, it seems to boil down to this: In 1989 Faith No More released an album called "The Real Thing," and several singles from that album for which videos were made. The video for "Epic" became very popular, and Patton was suddenly seen in silly clothing, swinging his long hair around, rapping to Faith No More's funk-metal sound, all over the world. Anthony Kiedis seems to have been oblivious to the fact that this sort of combination of funk, metal, and rap (always accompanied by bad clothing and hair) had been the trend on the West Coast for some time, and wasn't actually invented by his band. Envious of Faith No More's success, and angry that it seemed to have been achieved at least in part due to the wild frontman who he thought had stolen his "moves," he accused Patton of ripping him off in the press. Members of Mr. Bungle responded by gleefully threatening Kiedis with bodily harm in the press. Eventually Patton and Kiedis met in person, were polite to one another, and everyone lost interest.

Many years later, after Faith No More was long gone and the Red Hot Chili Peppers were hugely successful, the release of Mr. Bungle's "California" was pushed back by Warner Bros. so it wouldn't come out at the same time as the Red Hot Chili Pepper's similarly-named "Californication." Then, when Mr. Bungle were asked to play at some European festivals in the Summer of 1999, Kiedis threatened to cancel his band's appearance, and Bungle were dropped. That Halloween, Mr. Bungle retaliated by playing a show in Pontiac, Michigan dressed as the Red Hot Chili Peppers, complete with freqent heroin injections and covers of really bad songs. This resulted in Kiedis having them kicked off of some Australian festivals.

Fun quotes:

"OK, here's what happened, 'cause I know he has his opinion, now here's mine. In that interview the writer said, 'Are you guys sick of people ripping you off?' I said, 'Who are you referring to?' and he said, 'Well, Mike Patton in Faith No More.' So I told him what our drummer said, and yeah I watch that 'Epic' video, and I see him jumping up and down, rapping, and it looked like I was looking in the mirror. The thing is, I had no problem with him personally. I mean, I love 'The Real Thing,' and I liked his vocals on that record. I mean, when I heard the record I noticed subtle similarities, but when I saw that video it was like, 'Wait a second here, what the fuck?'" -- Anthony Kiedis

"I mean, the Chili Peppers is something I hadn't really thought of in years. And I'll go ahead and tell you this. Why not? I haven't told anybody else yet. We were looking at booking some Mr. Bungle shows in Europe this past summer, some big festivals, which is something we'd never done before. We figured it'd be a good thing: We'd get to play in front of a lot of people who wouldn't otherwise hear us. Our agent was in the process of booking these festivals, and it was becoming apparent that we'd landed some pretty good ones�one in France, another one in Holland, some big-name festivals. Turns out someone's holding a grudge! We were booted off several bills, including a really big festival in Australia, specifically because Anthony Kiedis did not want us on the bill. He threatened to pull the Chili Peppers if Mr. Bungle was on the bill. Now, rationalize that one! That's so fucking pathetic! I mean, this guy's selling a million records! We are not even a speck of dust on this guy's ass! What's the fucking problem? It's unbelievable." -- Mike Patton

"I would not have given two fucks if they played with us there, but after I heard about some Halloween show where they mocked us and read another interview where Patton talked shit about us, and I was like, you know what, fuck him and fuck the whole band." -- Anthony Kiedis

"We were booked, months in advance, to do eleven festival dates in Europe. Come Summer, we get a call from the three biggest of those festivals, all of them the same day, saying that we can't play, because the headlining band retains the right to hire and fire whomever they wish. We found out it was the Red Hot Chili Peppers, so our manager called their manager to find out what the hell was going on, and their manager was very apologetic, and said, 'We're really sorry, we want you to know this doesn't reflect the management's position, or the band's for that matter, it's Anthony Kiedis who wants this.'" -- Trey Spruance