Charles Fleischer may be just a little crazy - but that's definitely an asset for doing zany cartoon voices, offbeat characters in comedy routines or acting in a rabbit suit.

But perhaps that's getting ahead of the game just a bit.Fleischer isn't just another standup comic doing Saturday morning slide shows or kiddies' birthday parties. He provides the voice for a brand-new movie star of major proportions.

Fleischer is the voice of Roger Rabbit in what promises to be the summer's biggest hit - "Who Framed Roger Rabbit" (no question mark, please, the Disney people inform us).

And on cue Fleischer will not only shift into Roger's voice - he'll actually carry on conversations between Roger and himself. Also on cue, he can slip into the other voices he provides for the movie - Benny the Cab and the gangster weasels Psycho and Greasy.

After doing the voices for all three, at the same time explaining their origins - Psycho, he says, is a combination of Jack Nicholson and Mickey Mouse - at last comes Roger: "Jeepers, you know what Roger sounds like!" Fleischer says in the now-familiar, slightly tremulous, wobbily voice.

But that's not all. From his years of doing standup comedy involving various characters with various voices Fleischer just naturally switches to other voices during the course of otherwise fairly normal conversation. He also breaks into brief comedy routines without warning.

Example: He begins talking in a mock Italian accent. The interviewer notes that he has "a little Chico Marx in there." "Oh," Fleischer says still in his Chico voice, "a little Chico Marx would sound like this," and suddenly he's speaking in a squeaky high pitch that is impossible to understand.

Fleischer came to Salt Lake City earlier this week to promote "Who Framed Roger Rabbit," though the movie is such an amazing success it hardly needs promotion.

The immediate impression is that this guy is the perfect choice for Roger Rabbit. In fact, Fleischer himself looks something like a Toon, with his loping gait (a la Groucho, perhaps), his shoulders hunched up as if he forgot to remove the hanger from his jacket, his mop of curly black hair and bushy eyebrows, and a face so mobile that it stretches and changes to suit whatever is coming out of his mouth.

In other words, an interview with Fleischer is also something of an interview with some of his many characters.

But he does occasionally get a slightly serious tone in his voice.

"My approach to this role was as an actor, as opposed to just being a voice. I had them make me a Roger Rabbit costume - exactly the way Roger is." He gestures to the Roger Rabbit lapel pin he is wearing. "Little red overalls, bow tie and a pair of rabbit ears that I wore every day, and all my lines were recorded on the set as opposed to doing it in a studio."

He rehearsed with human star Bob Hoskins, then "projected" himself into the empty space Hoskins was acting with, the space where Roger Rabbit would later be drawn in. That way, Fleischer explains, Hoskins had immediate reaction to what he was doing on film.

"The director, Bob Zemeckis, saw me perform at The Comedy Store in Los Angeles about eight years ago and he remembered me and brought me in originally to help them audition the part of Eddie Valiant, the part that Bob Hoskins eventually got. I read Roger's lines to the actors auditioning for Valiant.

"At first they told me they just wanted a regular voice. Then they said they wanted a cartoon voice. Then after I had the job they told me to come up with some kind of speech impediment, because all great cartoon characters have speech impediments, so I developed the (and he goes into his Roger Rabbit voice, fluttering his cheek) `P-p-p-lease,' which I call the consonant cheek flutter - the CCF! And the method of acting that we used I call `trans-projectional acting."'

As for doing all this while wearing a rabbit suit, Fleischer says it may seem strange, but "I was playing a cartoon rabbit - how strange can it get?" Hoskins was at first taken aback, however. Fleischer suddenly becomes Hoskins, cockney accent and all: "What you doing? You're off-camera. What're ya wearing a costume - you're off-camera!" He adds in his normal voice, "But then later he thanked me because it was of great help to him in his process."

Fleischer says he would do more voices for Disney or Amblin (Steven Spielberg's production company), but says he doesn't care to do cartoons on a regular basis. Turning to a Liverpool, Beatles-style accent he says, "I don't want to be Yogi Bear, it's not my goal."

Then, returning to his own voice, "I'm happy being Roger. I'll do Roger forever. I love Roger, I think he's a great character. We're very close. Of all the characters I've ever played he's the closest to the real me.

"There's a line in the movie, `I'm a Toon - Toons are supposed to make people laugh.' I've been doing standup comedy for the last 15 years and certainly that's the goal of a standup comic, to make people laugh.

"There's another line in the movie where Eddie Valiant asks Jessica, Roger's shapely wife, `What do you see in this guy?' and she says, `He makes me laugh.' And I also have a beautiful wife who was attracted to me because of my ability to make her laugh."

Fleischer says he has been kicking around for 15 years, waiting for the big break, meanwhile doing standup comedy and acting in small roles in "Night Shift," the first "Nightmare On Elm Street" film, "Bad Dreams" and in a recurring role on TV's "Welcome Back, Kotter." He is now working on a record album of songs he has composed and plans to get his standup act back on the road, possibly in the fall.

But that's not all.

"I'm very much involved in science and the arts. I see them as all related. An analogy perhaps - a bicycle wheel: Starting at the center, the spokes radiate out - acting, science, comedy, music, and they all certainly end at the rim of the wheel.

"I've already written a book about a mathematical theory I've discovered, which has been acknowledged by mathematicians as a unique discovery in the field of group theory. (He's not kidding.)

"And certainly it is one of my goals to win the Academy Award and the Nobel Prize in the same year. Maybe a Grammy too, but I don't want to get pushy."

Of course, he's always had his heroes: "Jonathan Winters, Groucho Marx, Jimi Hendrix, Albert Einstein, Chagal, Picasso, Dali, Beethoven, Bach, the Beatles, Bob Dylan. It goes back to that bicycle wheel thing."

And even as a child he yearned to be in show business.

"Show business? I've always had that leaning, inkling, desire. (Then, as if he's on a phone) `Hello, "Thesaurus Are Us." What? A word for "Uh?" How about "Hmmmm."