The context to this quote is very useful. It's from the section when Beatty is telling Montag about the dumbing-down of life over the ages: shorten the books, add pictures, add games constantly, organize sports, cram things full of fluff, nursery to college to nursery:
School is shortened [...] Life is immediate
Thus the part
everything bang; boff, and wow!
promptly becomes clear from context. Life is flashy, in your face, full of empty comics and movies: bangs and flashes of smoke, 'wow's from whatever is currently in line of site. 'Boff' I'm not familiar with; could be slang from somewhere, but in context the meaning is clear: something flashy and in your face.
Life becomes one big pratfall
Is also, therefore, clear from context: the general impression is that life is something of indulgence and emptiness, without any clear meaning. And this is what the people want! This is why Beatty's speech to Montag is so powerful: this isn't the fault of the firefighters. It's the fault of the people themselves.