What,...
Ejemplos:
What, are you full?
What, is he talking to me?
What, do you think I'm stupid?
What, you want me to do it all myself?
En cada una de las oraciones de arriba, la palabra what se puede omitir sin cambiar el significado fundamental de ninguna manera. Sin embargo, la palabra añade algo importante, y hace que la oración suene mucho más natural en un contexto hablado. Esta palabra no se pronuncia con una entonación asecendente (como si fuera una interrogativa), sino descendente. Este uso es sumamente común, pero no se me occure nada equivalente en español, a no ser que se diga "qué" de la misma manera.
¿Sugerencias'
17 Answers
As an American,
the problem is that we have adopted a wide spread usage of rhetorical questions merged with sarcasm. This means that it is strictly a conversational and cultural thing, and is not highly applicable any where else. I am not an expert on other languages, but it could partially be because of how flexible grammatical laws are in English, specifically in America. When one is showing any form of friendship for example, these rules do not generally apply, and thus many new phrases and laws keep getting formed because we relax these laws.
Also, there are generally two views on sarcasm in America.
There is the converstaional sarcasm that is not complete without the proper tone of voice. This means that in order to get away with sarcasm, then one must have a friendly tone, and it can not be about something serious.
There is also the more serious sarcasm. There are simply some things that you do not joke about. An example of this would be something that someone finds deeply personal, such as a pet dying or something along those lines. The sentence, "What, did you like him'" isn't appropriate.
From what I have been able to decipher, most English is mainly about meaning. American English however, is all about tone and general idea, not exact meaning of words.
Maybe one of the reasons why there isn't a way to say it as clearly or in the same way in Spanish as you are able to in English is, from what I have observed, sarcasm isn't viewed as highly outside of the United States. I was always told that sarcasm was mean and rarely viewed as funny.
I can't think of adding the same nuance in Spanish without including an iterrogative, which as you said is not the true meaning or purpose of saying 'What...'
In a different thread, someone suggested vaya for expressing mild surprise . . . I don't know if that fits'?
¡Vaya! No se me había ocurrido, pero claro que sí. Eso pega fenomenal. 
For me, your sentences would be better written like this:
What? (or What!) Are you full?
What! (or What') Is he talking to me?
What? (or What!) Do you think I'm stupid?
What! (or What') You want me to do it all myself?
I say this because in each case the first word is a question by itself or an exclamation. In that context, there would be some rising of intonation at the trailing off of the first said question or exclamation. This would be followed of course by the second or real question.
Moe, not having spent much time in Canada, I can't comment on how this is said up there, but you obviously don't understand what I am talking about. The "what" here is not at all an exclamation separate from the rest of the sentence. In fact, the words are usually run together very tightly, like "Whaddaryou full'" This is quite distinct from the phrases as you have written them, which we also use, but which have a very distinct nuance. The one I'm talking about is a way of kidding someone, and any American would know exactly what I'm talking about if they heard me say it (and I suspect you would, too).
James:
I was unsure of your sentences, in English, when I first saw them. By the time I clued in to what was bothering me, I was unable for several hours to re-enter the thread. It was a glitch on my computer. Sorry for the delay, but here I am.
For me, your sentences would be better written like this:
What? (or What!) Are you full?
What! (or What') Is he talking to me?
What? (or What!) Do you think I'm stupid?
What! (or What') You want me to do it all myself?
I say this because in each case the first word is a question by itself or an exclamation. In that context, there would be some rising of intonation at the trailing off of the first said question or exclamation. This would be followed of course by the second or real question.
I also wondered how this might be handled in Spanish. I contemplated "¡Cómo!" or maybe "¿Cómo'". When I checked in SpanishDict.com's dictionary, I found this item:
*¡cómo! ¿no te has enterado? -> What! You mean you haven't heard? *
or possibly a variation on that theme such as:
¡Eh! ¿no te has enterado? -> Hey! You mean you haven't heard'
It's just an idea. Something else for you to consider.
Best regards
Gracias por toda la ayuda. Ahora creo que lo entiendo. Tendré que hacer caso a lo que dicen los hispanohablantes en tales contextos.
En cuanto a "me doy entendido," claro que sí que es un uso regional, ya que es usado aquí en mi casa por mí (guiño). Es lo que pasa cuando no checo lo que escribo.
In a different thread, someone suggested vaya for expressing mild surprise . . . I don't know if that fits''
En español se usarían también ambas entonaciones. Por cierto, no sé si tu última pregunta se usa en América, pero a mí me suena rara. En España solemos decir "¿Me explico'"
¿Me doy entendido?
A mí me parece una traducción directa de "Am I making myself understood'"
De usarlo será en Méjico.
En la primera, se pronuncia con una entonación asecendente, y significa incredulidad. Es decir, el hablante no puede creer que el otro está satisfecho ya. Esto no es lo mismo que la segunda, que también tiene el matiz de incredulidad, pero no tan fuerte, y tiene un matiz de burla o sarcasmo. ¿Me doy entendido?
En español se usarían también ambas entonaciones. Por cierto, no sé si tu última pregunta se usa en América, pero a mí me suena rara. En España solemos decir "¿Me explico'"
'Se puede usar "como" en vez de "que" en estas oraciones?
¿Cuáles oraciones?
Pues fíjate que yo creo que los tonos de cómo serian mucho más explícitos.
¿C'mo? - gran sorpresa
¿Còmo? - repita, no entiendo
¿Cómo? - no me digas, no te creo
¿C'mo? ? a mí no me hablas así, ok?
Mejor me voy a la cama, ya es un poco tarde. 
What? You're full?
What, you're full?
En la primera, se pronuncia con una entonación asecendente, y significa incredulidad. Es decir, el hablante no puede creer que el otro está satisfecho ya. Esto no es lo mismo que la segunda, que también tiene el matiz de incredulidad, pero no tan fuerte, y tiene un matiz de burla o sarcasmo. ¿Me doy entendido?
A mí es claro. Pero creo que hay un tercero entonación, lo que tiene el matiz de preocupación. Escribiría este caso como el primero ejemplo que tu escribiste. El primero caso que describes, escribiría:
What! You're full'
'Se puede usar "como" en vez de "que" en estas oraciones'
Podríamos intentar algo con los tonos del Idioma Chino.
¿Qu? pásà? - Tono impaciente, agriado, enojado
¿Qué pàsa? - Tono amistoso, casual, moderado
¿Qu? p'sa? - Tono de asombro, sobresalto, crítica
¿Què pàsa? - Tono desafiante, chocante, pugnante
¿Que pasa? ? Tono neutral, sereno, pacífico
No se si mis tonos correspondan exactamente con cada adjetivo'es solo una idea.
Pues, no veo por qué no se puede decir de ambas maneras también en español.
Gracias, Di. Espero ver otras opiniones también.
