Using quotation marks in direct speech

Question

My native language allows omitting quotation marks in sentences containing direct speech when the borderline between the "wrapper" sentence and the quoted speech is obvious and does not produce grammatical ambiguity.

To my understanding, the rules of direct speech in English require quotation marks in all cases. If that is correct, the joke below makes no sense because if it were about prohibited writing of a certain phrase, it must be spelled in quotes and with first word capitalized:

Do not write, "Your essay", on this page.

Without the proper punctuation, can the joke be valid?

Answer 1

Your question is the result of the interplay of two factors:

1. Humor often results from "breaking rules"
2. Punctuation rules, especially in informal contexts, are often ignored.

But in formal contexts, quotation marks should be used in direct quotation.

Answer 2

The joke, as you say, is invalid due to the way the phrase is written on the page.

If the quotations were there, then the joke would be fully valid, but without the quotes, the phrase has an entirely different meaning just as you said.

This said, when people say it out loud, it is impossible to tell the difference (if they say it wrong - if they say it correctly then there should be a pause at the comma, but everyone says it wrong) and the joke stands.

As such, people take the joke as 'valid' due to the way it would be said out loud, however people would normally know that this is incorrect, and know the correct meaning.