In the history of antagonistic comedy duos, few achieve the boiling tension of Bill Murray and Richard Dreyfuss in What About Bob?

They were the perfect opposites: the nearly mullet-sporting Murray, flailing around with his wildly improvised dialogue and eccentric physicality; the clean-cut Dreyfuss, a master thespian with studious delivery suited for Shakespeare. But the costars didn't fall neatly into a goofball/straight-man archetype for the film, which hit theaters on May 17, 1991. Drawing on a very real on-set animosity, they annoyed each other into a surprisingly complex character dynamic.

Murray plays Bob Wiley, a lonely, agoraphobic hypochondriac who leeches like a parasite onto his therapist's summer vacation. Dreyfuss plays Dr. Leo Marvin, a wealthy, self-aggrandizing egomaniac who slowly watches his family rebel against him — and his cushy lifestyle vanish — due to one ill-fated patient arrival. It's hard to distinguish between hero and villain in What About Bob?, the still-underrated dark comedy from director Frank Oz and screenwriter Tom Schulman. But that blurriness is part of the fun, transforming what could have been a generic family romp into something more unsettling — and, ultimately, funnier.

But early on, who wouldn't root for Bob?

We first see the character nearing a breakdown in his ordinary apartment, repeating a self-improvement mantra ("I feel good. I feel great. I feel wonderful.") while aggressively rubbing his temples. His only company? A goldfish named Gil. And our protagonist braves exiting his home like he's wandering into a post-apocalyptic wasteland: clutching doorknobs with tissues, walking sideways down his front step, standing with a zombie-like posture that only hints at the scale of his phobias.

Watch the 'What About Bob?' Trailer

He grows more sympathetic only after we meet the unlikable Dr. Marvin. Distracted by his newly published book, Baby Steps, and forthcoming Good Morning America interview (to be staged against the idyllic backdrop of Lake Winnipesaukee, N.H.), he accepts Bob as a patient referral from a panicked colleague. (The latter is briefly shown sweating and gathering his plants for a swift exit — maybe from his practice, maybe from the business altogether.) He's an invincible elitist and future TV star — how could one more needy everyman kill his vibe?

Quite easily, it turns out. Dr. Marvin is just trying to quickly clear his to-do list before heading off for a monthlong vacation, but the world-weary Bob proves a bit more challenging than a quick drop by. "I have a real problem moving," he tells his new therapist, also citing "fingernail sensitivity" and "pelvic discomfort" among his various ailments. At one point, he mimics Tourette's syndrome by shouting a string of obscenities — the logic being, "If I fake it, then I don't have it." Bob also reveals that he's divorced: "There are two types of people in his world: those who love [Neil Diamond] and those who don't. My ex-wife loves him." Dr. Marvin doles out some valuable advice from his book — charging Bob, naturally, full price for the text — and sends him on his way. But our titular character stays in his orbit like a nagging gnat.

Bob eventually recruits a prostitute to impersonate the doctor's sister, earning some phone time with his new self-help guru. When his request for a session proves unfruitful, he impersonates a detective, visits the practice's phone operators in person and weasels his way into learning Marvin's New Hampshire address.

After some cleverly written chess-piece moving — involving a nearly panic-inducing bus ride, some desperate pleading, the assistance of an immigrant couple that despises the doctor and a prescription for a "vacation" from his problems — Bob shows up at the family's doorstep with a backpack, his goldfish and newfound optimism. As Bob grows happier and more adjusted, Dr. Marvin descends into despair. His GMA interview is a train wreck, spurred on partly by Bob's lingering presence.

Even worse, the family grows to love Bob for his seemingly childlike personality — helping young "Siggy" (Charlie Korsmo) overcome his fear of diving; giving teenage Anna (Kathryn Erbe) an ally for fun in a strict household; offering Marvin's wife, Fay (Julie Hagerty), the freedom to laugh.

Of course, they all disregard Bob's unhealthy obsession with Marvin, a behavior most people would view as troubling, if not criminal. (As multiple, hilarious YouTube parodies have proved, it's easy to re-edit What About Bob? into a stalker-styled thriller with only the aid of creepy editing and dramatic music.)

Watch a 'What About Bob?' Parody Trailer

In a subtle but brilliant twist, the lead characters' roles — and, up to a certain point, our sympathies toward them — superficially reverse. Bob is seemingly the more stable of the two, even offering his opinion about psychiatric medication to Marvin's doctor.

Meanwhile, as Bob becomes more beloved, Dr. Marvin deploys more drastic means of ending that problem — including an attempt to institutionalize his nemesis and, eventually, blow him up with explosives. (Naturally, Bob thinks it's all a ruse — he comes strolling back to the Marvin house, singing, "Your death therapy cured me, you genius" to the tune of "For He's a Jolly Good Fellow.")

What About Bob? ends in an even darker place: the vacation home in rubble, Marvin in a catatonic state, Bob marrying the former doctor's sister — and only stirred back to normalcy with the horror of the wedding ceremony. (We learn via recap text that Bob later wrote his own best-selling book, Death Therapy, prompting a lawsuit from Marvin.)

Though their relationship never reached a Bob/Dr. Marvin level of unpleasantness, Murray and Dreyfuss notoriously clashed on set due to creative differences and personality clashes. "The script wasn't nearly as annoying as I could be, so I had to improvise a lot in the movie," Murray told Deseret News after the film's release. "And even what you eventually see in the movie isn't close to how really annoying I can be when I put my mind to it. … There's always more annoying behavior right below the surface."

In the same interview, Murray detailed "all sorts of annoying things" he did to Dreyfuss during the shoot. "While he was talking, I got in real close to crowd him, I put my head on his shoulder, screamed into his ear," he said. "Some of that was even in the script …no wait, none of that was in script. I made it all up. … It was quite liberating to play someone like that. When you've got as many problems as Bob has, anything goes. Anything that I could think of to annoy someone in a scene, particularly if it was Dreyfuss, I went with it."

In a 2019 Yahoo! interview, Dreyfuss called Murray an "Irish drunken bully" while describing one alleged altercation. "[Murray] came back from dinner [one night] and I said, 'Read this [script tweak]; I think it's really funny," he said. "And he put his face next to me, nose to nose. And he screamed at the top of his lungs, 'Everyone hates you! You are tolerated!' There was no time to react because he leaned back and he took a modern glass-blown ashtray. He threw it at my face from [only a couple feet away]. And it weighed about three quarters of a pound. And he missed me. He tried to hit me. I got up and left."

Who knows how Bob? would have turned out if the actors had gotten along. In hindsight, it sure seems like the conflict fueled the comedy.

"How about it? Funny movie. Terribly unpleasant experience," Dreyfuss told A.V. Club in 2009. "We didn’t get along, me and Bill Murray. But I’ve got to give it to him: I don’t like him, but he makes me laugh even now."


Rock's 60 Biggest 'Saturday Night Live' Moments

More From KLUB Tejano 106.9