Ozzy Osbourne never meant to bite the head off a bat.

Or urinate on the Alamo.

He didn't play "heavy metal" and didn't even have that much to do with the dark, ungodly vision of Black Sabbath.

As we glean from "I Am Ozzy," things tend to happen to him beyond his control -- not that control is in any way part of his nomenclature.

It makes the Prince of Darkness' autobiography funny, frustrating, fascinating and impossible to put down, much like the outrageous Motley Crue memoir "The Dirt." Ozzy empties what's left of his damaged brain, managing to dredge up sympathy even as he delivers the straight dope on his rampant substance problems, extramarital lapses, neglectful parenting and abusive episodes with two wives.

From the get-go, Ozzy -- born John Osbourne -- was more goofball than devil, starting in elementary school when dyslexia combined with a lack of fighting or athletic skills forced him into class clown status. From school days on up until his White House visit and beyond, he has continued to play that role, even in a genre that took itself as seriously as heavy metal in the '90s.

In his grim, working-class hometown of Aston, England, the only opportunity for a poor boy with lousy grades was a factory gig, and Ozzy failed miserably at that. The one job he enjoyed, ever so briefly, was one at a slaughterhouse in 1964 shooting cows in the head with a bolt gun.

"I was a natural at killing animals," he gloats, although he'll later adore his pets. That job went bad when a co-worker splashed him with blood as a practical joke, and he whacked the guy in the face with a pole.

His brief career as a burglar ended when he got busted for "nicking" a "telly" and got scared straight doing three months in Winson Green prison. Although he would spend his share of nights in jail, he managed to make that his last stop in prison -- behind bars, at least.

Ozzy's liberation was music, prompted by his thrill at hearing the Beatles, whom he idolizes to this day. With a vocal PA system his dad took out a loan to buy, Ozzy placed a sign in a music store that read "Ozzy Zig Needs a Gig." As fate would have it, it brought guitarist Tony Iommi and drummer Bill Ward literally to his front door. When Iommi, a true talent and stud, saw who Ozzy Zig was, he turned to Ward and said, "He's Ozzy Osbourne and he's an idiot. C'mon, let's get out of here."

For whatever reason, they gave him a break, and so began the era of ... the Polka Tulk Blues Band. Yes, the Polka Tulk Blues Band, taken from Ozzy's mum's armpit powder. That was the original name of Black Sabbath, then peddling in American blues covers, just like every other British band.

This "rise-of" portion is typically the highlight of any biography, and it is here as well, with tales of broken-down vans, bar fights, band clashes and Ozzy's bouts of stage fright. At one point, when the band was called Earth, Iommi departed for Jethro Tull but immediately returned, saying he couldn't have the same laughs with those guys.

Upon his return, it struck the guitarist that they should make "evil" music, based on the queues they saw for horror films at the local theater. "Black Sabbath," the song, was born, followed later by the name change and overall faux-Satanic persona.

Of the sound, Ozzy writes, "I've always had a bee up my arse about the term 'heavy metal.' ... As far as we were concerned, we were just a blues band that had decided to write some scary music."

People immediately were taken aback. At a town hall near Manchester, the manager screamed "Stop!" on the first ominous notes of the show, thinking Earth was going to play Top 40 covers such as "California Dreamin' " and "Mellow Yellow."

Iommi was churning out the riffs, and the bookish Geezer Butler was writing most of the lyrics, with Ozzy chipping in. Those who probe Sabbath lyrics for meaning only to be befuddled will be heartened by this insight from Ozzy on "Fairies Wear Boots": "To this day I have no idea what that song's about, even though people tell me I wrote the lyrics."

Although critics, along with Ozzy's parents, shunned Sabbath, the band was embraced by a post-hippie fan base, not to mention various occultists and Satanists, who drove Ozzy nuts. When the band was asked by "freaks with white makeup and black robes" to play a cemetery gig, Ozzy told them, "Look, mate, the only evil spirits I'm interested in are called whisky, vodka and gin."

Then it was cocaine, once the money poured in from songs such as "Paranoid" and "Iron Man." In typical fashion for '70s bands, the white powder fueled Sabbath's early productivity before ultimately bringing the band to its knees. They even wanted to call the fourth album "Snowblind," as Ozzy says, "We all had moments when were so [messed] up that we just couldn't function." The way it worked, he writes, is that when the band was selling millions of records, rather than getting checks from management, they got drugs, cars, houses, horses, whatever they asked for.

Drugs pervade about the last 250 pages of the 388-page book. Cocaine, hash, LSD, Vicodin, Valium, antidepressants, booze ... Ozzy couldn't shake them, through his dismissal from Sabbath, his abusive marriage to Thelma Mayfair, his successful solo career with the regrettable bleached hair, his life with rough-tough Sharon Arden (who punched back), the full-family MTV reality show, the stints in Betty Ford, etc.

You can't read "I Am Ozzy" without wondering how he remembers anything. Now at 61, the indestructible and more clear-headed Ozzy notes in the foreword that his "jelly brain" might have twisted some of the memories. Nonetheless, he relays stories of almost killing a vicar with a cake of hash, snorting a line of live ants to out-crazy Motley Crue, having dinner with Frank Zappa, losing guitarist Randy Rhoads in a freak plane crash, acting like a screaming lunatic at a White House dinner and being a total pig to Brian Wilson.

And then there was the bat. A drunken Ozzy had already chomped off the head of a dove during a record company stunt. In January 1982, Ozzy thought a toy bat landed on the stage. When he picked it up and bit down, "my mouth was instantly full of this warm, gloopy liquid with the worst aftertaste you could ever imagine. ... Then the head in my mouth twitched."

It didn't make Ozzy any friends with animal rights groups, but it certainly sealed the deal on his madman reputation then and for all eternity.

In "I Am Ozzy," you get the madman, the clown, the burglar, the villain and the wounded kid underneath who has had a blast while apologizing for a good chunk of it.

Critics Andrew Druckenbrod and Scott Mervis talk about music on "The Beat," available exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.