Boy meets girl

[planet]

Boy meets girl.
Boy falls for other girl.

'boy' and 'girl' are countable nouns, aren't they?
Grammar books explain that a countable noun always takes either the indefinite (a, an) or definite article (the).
They need the article 'a', 'the' or plural forms, don't they?
You know, You often see "Boy meets girl" in the titles of novels and movies etc.
I wonder why underlined words are without the aricle.

[Barb_D]

It's a very specific usage for describing the plot of novels, plays, movies, etc.

"The plot is nothing new: you know, boy meets girl, boy loses girl, boy gets girl. Totally predictable, but the actors are appealing, so you may enjoy it anyway."

[planet]

Thanks a lot.
Do you happen to know the website where the specific usage is explained?