Then came Tootsie (1982), playing Dustin Hoffman's roommate. He ad-libbed his way through the script. "They kept on saying, 'Just react.' So I would come up with lines like 'That is one nutty hospital' or 'I'm just afraid you are going to burn in hell for all this' ... Then they would write these down as scenes and say, after a few days, 'Come up with something else.' It was like that through the movie."
He also learned about power play on a film set, witnessing the constant arguments between Hoffman and director Sydney Pollack. "Dustin would throw a fit, and the crew just stood back and watched," he says. "He's a perfectionist. These things explode, but it is always about getting the right sort of film. Sydney would have a go back and they'd be like these two prize fighters, with veins bulging in their foreheads. I still felt like the junior guy in movies, so I tried to lighten the mood." That took the form of Murray pretending to have a fit himself. "Everyone knew I was kidding," he says, "but it helped defuse one or two situations."
I just think it's instructive that (to me, anyway) Murray's laid-back, semi-improvised performance holds up better than Hoffman's painstakingly rehearsed and thought-out performance.
Here's the scene where Murray improvises a series of increasingly incoherent rants about the theatre: