Many of us are probably familiar with the expression "Read my lips" as in,
"John, aren't you going to the party tonight?"
"Read my lips: no."
There's kind of a sarcastic emphasis, which is designed to underline the definite nature of the reply. Is there a French equivalent, and what is it, if there is?
Read my lips can be translated by lis sur mes lèvres but that doesn't match the English idiom.
It is almost only used non figuratively, for example if the location is too noisy for the talk to be heard, or if you want to communicate without emitting sounds just by simulating speech.
There is a good movie named Sur mes lèvres which English title is precisely "Read my lips". It is about a woman almost deaf that effectively lip-reads.
To match "read my lips", you'd rather introduce your sentence with:
Écoute bien ce que je vais te dire : non ! (colloquial)
Écoutez bien ce que je vais vous dire : non ! (formal)
meaning "listen carefully to what I am going to tell you…."
Note that lis mes lèvres is not idiomatic.
There's no word-for-word translation of this English idiom that I know of, so I'd suggest any expression of emphasis as replacement, such as
Je vais te dire un truc : non.
Il n'y a pas moyen (= emphatic no)
Tu sais quoi ? Non
Je vais être franc : non
Écoute-moi bien : non
You can also say "suivez mon regard" which translates as follow my look, but means you see what I mean, what I'm talking about.
It also has a 2nd sense, when you don't want to say something very obvious, or like when you mean a person physically present. "There a some who think they are above the law, follow my look..."
I'm In the first sense it's very close but not 100% on read my lips.
There are many ways to firmly assert an opinion, some of them have already been mentioned. They are usually openers, among which:
In the non-ironic sense (“I'm about to say something important”), any method for emphasis will do. For example:
Since George Bush used the phrase in 1988 and his political opponents later pointed it out as a lie, the phrase has acquired an ironic bent. Any of the phrases above can be used ironically, but context is required to make the irony apparent, you can't rely on the cultural implication like in English.
If the implication is “everyone knows that what I'm about to say is a lie”, there is a somewhat similar phrase, of similar vintage, from a TV debate between the two main candidates for the the 1988 French presidential elections. The original exchange was:
Jacques Chirac — Pouvez-vous vraiment contester ma version des choses en me regardant dans les yeux ?
François Mitterrand — Dans les yeux, je la conteste.
Literal translation:
— Can you really dispute my presentation of the facts, eye to eye?
— Eye to eye, I dispute it.
It was widely known that Mitterrand was lying, but during the debate, he didn't let on. Since then, at least in France, the phrase “Dans les yeux, …” or more often the misquoted phrase “Droit dans les yeux, …”, has become a way to say “I affirm the following thing, even though you and I know that I'm lying”. Common variations include “droit dans les yeux, je vous le dis” or “droit dans les yeux, je vous l'affirme”. This is probably not known outside France and may not be known to younger generations who weren't following politics in 1988.
Parfois, on prend l'expression anglaise au pied de la lettre, c'est-à-dire qu'on dit « Non » sans vocaliser, en exagérant le mouvement des lèvres et en ponctuant avec le reste du visage notamment en faisant de grands yeux ronds.
