Author Bill Geerhart poses Wednesday with his correspondent’s tools of the trade — a child’s writing tablet and a pencil — by which he created his new book, “Little Billy’s Letters,” at his home in Los Angeles. Geerhart was better known to some of the famous and infamous as “Little Billy,” punking them by posing as a school boy writing letters to them asking questions out of the mouths of babes. Their correspondence back is compiled in “Little Billy’s Letters,” out this week.

Washington ? Over the years, “Little Billy” learned much from the country’s top minds.

Secretaries of state, touched by the 10-year-old’s handwritten letters on grade-school notepaper, wrote back advising him how to settle a treehouse dispute with his sister. O.J. Simpson’s lawyer told him how to get off the hook on accusations he destroyed a doll. A publisher of racy magazines, asked whether there was a version for kids, told him to read the Sears catalog instead, and “you’ll be 18 before you know it.”

Billy also turned to twisted minds for their counsel. He wrote to notorious criminals asking whether he should stay in school. Son of Sam told him not to waste his life, like he did; the Unabomber merely wished him luck.

It was all a big setup. Little Billy was actually grown-up Bill Geerhart, punking the famous and infamous by writing letters to them asking questions out of the mouths of babes. Their correspondence back — humorous, head-scratching, poignant — is compiled in a book, “Little Billy’s Letters,” out this week.

Killing time

Geerhart, who admits to a history of making crank phone calls and other mischief in his youth, collected the letters over 15 years, starting in the mid-1990s while he was killing time as an unemployed writer in Los Angeles.

Most of the letters in the book go back to a time before e-mails took over written communication. But some are recent. In 2008, Sarah Palin’s dad, Chuck Heath — handling the deluge of mail for his daughter, the Alaska governor and Republican vice presidential candidate — declined to take Billy hunting wolves by air. “No wolf hunting from helicopters here,” scribbles Heath.

Career counseling

For career advice, Billy — who was leaning toward convenience store clerk because he would have access to video games on the job — polls those in other fields, including assisted-suicide figure Dr. Jack Kevorkian. From his prison cell, Kevorkian responds, “sometimes I wish I was a 7-11 clerk!”

As Billy mounts a campaign for third-grade class president, he gets good-luck wishes from former President Gerald Ford and former Vice President Dan Quayle.

Advice for life

Less civic-mindedly, Billy writes to Anheuser-Busch asking “if there is a beer for kids” just as he asked Hustler magazine publisher Larry Flynt about porn for the pint-sized. No dice.

Flynt writes that Billy could subscribe to Hustler when he turned 18: “Until then, you should read the Sears & Roebuck catalog.” An Anheuser-Busch executive rats on him, sending his parents a brochure on how to talk to kids about drinking.

Robert Shapiro, member of the legal “dream team” that won O.J. Simpson’s acquittal in the 1994 slayings of his ex-wife and her friend, was full of ideas when Billy wrote to ask for help defending himself against allegations that he — not his dog — destroyed his sister’s doll.

“Is there any forensic evidence that will support your theory that the dog killed the doll?” Shapiro replied. “Were any scraps of doll clothing found near his dog house, perhaps? How about tooth marks on the doll’s remains (assuming there were remains)? If so, a good forensic dentist should be able to match them to the dog.”

David Berkowitz, the Son of Sam slayer who killed six women in a late-1970s rampage in New York City, tells Billy, “don’t do self-destructive things” and opens up about his own grief and guilt. Murderous cult leader Charles Manson merely beefs that he’s not getting his Los Angeles Times in prison.

Seeking the wise counsel of retired diplomats for how to stop incursions by his sister “Connie” into his treehouse, Billy gets former secretaries of state James Baker and Henry Kissinger to bless a handwritten, one-year “treaty” that would keep Connie out — though Baker thought it should last two years.

Probing the high court’s opinions of McDonald’s menu items, Billy learns that then-Supreme Court Justice Sandra Day O’Connor favors the Big Mac, while her colleague Clarence Thomas replies, “I like almost everything there.” Writes Associate Justice Harry Blackmun: “Almost anything they put out is acceptable. I like to go to Roy Rogers, too, for a beef sandwich. But I hope most of all that you eat something more than what these fast food places put out.”

And when his beloved dog “Tippy” dies, Billy is gently consoled by cryonics company executives who learn that he has put the animal in a meat freezer and wants to bring it back to life.

Almost outed

Geerhart, who works as a record producer in Los Angeles and is curator of a Cold War pop culture Web site, once had Little Billy’s exploits catch up with him.

As Billy contemplated which religion to join, he asked officials at the Church of Jesus Christ of Latter-day Saints to verify that “you get to wear cool underwear and have extra wives.” The inquiry earned Geerhart a visit from a pair of Mormon missionaries wanting to meet the youngster. Geerhart concocted an excuse for Billy’s absence and dutifully snapped a picture of the tie-clad missionaries in his disheveled apartment.

Naturally, he includes the photo in the book.