The two-character play, whose script is taken almost verbatim from Zweibel's 1997 book of the same name, details the 14-year-long, sibling-like relationship between Zweibel and Radner, the irrepressible comic actress who died of ovarian cancer at age 42 in 1989.
According to Zweibel, it was truly (platonic) love at first sight.
"There was an instant connection," offered Zweibel, a giant of American comedy whose credits include co-creating the HBO series "The Larry Sanders Show" and co-writing Billy Crystal's Broadway hit, "700 Sundays," in addition to creating some of Radner's most indelible characters, including the clueless "crusading reporter," Roseanne Rosannadanna.
"We got each other comedically. We made each other laugh. It was very exciting, this whole new show; no one had ever worked in television before, with very few exceptions, like Lorne and probably Chevy [Chase]. So we were just a bunch of kids."
That instantaneous connection to Radner, he continued, "was a neurotic Jew thing. We spoke the same language that way. We got each other. I was probably the guy version of her, and she was probably the girl version of me. The most natural thing was for us to hang out and cultivate whatever creative partnership we were forging.
"We grew from a very similar creative force, whatever that was. We looked at the world the same way. We looked for the silly and we looked for the ironic. And both having similar backgrounds, we had a shorthand, which is what you look for."
Between the book and the stage adaptation, "Bunny Bunny" has been in the public realm for 16 years - not bad for a project borne out of grief rather than creativity or commercial considerations.
According to Zweibel, he had a tough time dealing with Radner's death. As a result, he started writing down as much of the pair's dialogue as he could remember. The idea was to use the exercise as therapy, not a career move. But his friends wouldn't let Zweibel keep his memories to himself.
"I had to be talked into it," he recalled. "I did it for my own therapy just to get over it. I showed [pages] to my wife and I showed it to Mel Brooks, and I showed it to Carl Reiner, and I showed it to Garry Shandling. I showed it to all these people who knew me and Gilda. It was just a way of saying, 'Remember this?' They all said, 'You should publish this.' "
Zweibel, who described "Bunny Bunny" as "basically a love letter that was written post-mortem," reluctantly agreed with his famous pals, but insisted on conditions before he'd sign a publishing deal (with the Hal Leonard Corporation): He had to get the blessings of Radner's widower, actor Gene Wilder, and her mother and brother, and all proceeds from the book's sale had to be earmarked for Gilda's Club, which provides support for cancer victims and their loved ones.
As for the transition from printed page to stage, Zweibel conceived "Bunny Bunny" as a theater piece in order to maintain control over its authenticity and integrity. He explained that filmmaking friends, including Rob Reiner, wanted to turn "Bunny Bunny" into a movie, but he resisted in fear that its producers would add contrivances and made-up scenes in order to enhance the storyline.
Zweibel admitted that he is again (still?) being lobbied by Hollywood to turn "Bunny Bunny" into a movie. And he admitted that he is still wary of losing creative control over this most personal of projects.
"With all due respect," he said dryly, "I'd rather Queen Latifah didn't play Gilda."
Independence Studio on 3 at the Walnut Street Theatre, 825 Walnut St., show times vary, $40, $35 and $30, 215-592-9560, 1812productions.org.