The “Heeeere’s Johnny!” line that followed the door’s destruction was improvised by Nicholson and lifted from the intro to The Tonight Show Starring Johnny Carson.
Kubrick originally shot the scene with a fake door, but Nicholson, who once trained as a fire marshal, chopped it down too quickly.
axe scene in Stanley Kubrick’s 1980 classic The Shining has become so iconic it’s quite difficult to separate it from its infamy and view it as simply a moment among many great moments in the film.
Nevertheless, it is a masterfully deranged performance from Nicholson, whose wild eye, eyebrow and mouth movements convey sheer mania.
…
The Shining (1980) - Here's Johnny! Scene (7/7) | Movieclips