"On the nose" simply means that in your dialogue, people say exactly what they're thinking.
Unless you're writing Data or Spock, that's generally not so great. In real life, people tend to avoid saying what they really think. They talk in circles, they hint, suggest, say things elliptically or simply with a look. Maybe they even say the exact opposite of what they mean, sometimes sarcastically, sometimes not.
Look at these two dialogue excerpts. The first is quite on the nose. The second is not. Which is better dialog?
RYANHmm. Or how about this:
Are you accusing me of stealing?
Well, I do jump to conclusions
a lot. But you seem generally
untrustworthy, and I'm still
gun-shy from my disastrous
failed marriage, so yes, I am
accusing you of stealing.
RYANObviously the second example sounds a bit more authentic, and less stupid to boot... although the first version could work for a quirky character in a comedy.
Are you accusing me of stealing?
Huh? Of course not! I just...
No, no, definitely not.
Jody sighs, uncertain.
You want your dialogue to sound like something a human might actually say, right? Read it ALOUD. Have a friend read it with you. Does it flow naturally? Does it seem clunky? How would you rephrase it into something perhaps not so on the nose, but that still gets the meaning across? Remember you can use all sorts of tricks--a coy look, a roll of the eyes, a dismissive wave, a sigh, biting of the lip, a raised eyebrow, etc.
And then even when someone explains it to you, more confusion inevitably follows. So is it ever okay to write on the nose? The answer is YES.
Here's the rule of thumb: There are two places in the script you should be right on the nose in your dialogue. The first is when you're describing your protagonist in the first ten pages. You want to make sure people GET what your protagonist's dramatic flaw is--the problem he's going to arc out of by the end of the story. So it doesn't hurt, for example, to have a supporting character say about the protagonist...
GEORGESmack! Yep, that one probably deviated someone's septum it was so on the nose. Yet it's often necessary. Even if we SEE (and we should) several instances of Ryan's aforementioned behavior, it's often necessary to "hit it hard" and state the dramatic need clearly. This is so folks GET IT. It also tells you what the theme of the story is, or what the story will REALLY be about--George's evolution into a better person.
Man, Ryan might really get ahead
if he didn't keep shooting himself
in the foot with his
The other time we want to be on the nose is when we're telling folks exactly what the plot is, or in other word's, the protagonist's goal. This generally comes at the end of Act 1 and propels us into Act 2, like this:
RYANThere you have it--very succinctly we have the protagonist tell us exactly what he intends to spend the next two acts of the movie attempting to accomplish. No beating around the proverbial bush here. Hit that puppy on the nose.
Fine. I'll get your damn prize-winning
Cavalier King Charles Samoyed back
to Anchorage in time for the fricking
dog show, all right? And no bounty hunters
or representatives from FEMA are going
to stop me!
One other time you might want to be on the nose: in your description. Keep in mind that the "on the nose" note generally applies only to dialogue. Your description should be lean and clear. You do not want to risk losing anyone by being cute or sarcastic or evasive.
Now get back to writing, folks! (I know I won't. See piece on procrastination below...)