The expression quedarse a cuadros or dejar a alguien a cuadros is a widely used colloquial expression among young adults to express when someone is unresponsive, or does not understand what other people say, or just does not react to any situation. An easier way to put it is that someone is shocked, astonished or very surprised by something.
Some equivalent expressions in English would be to be surprised, to be astonished or to be shocked.
Las noticias de hoy me han dejado a cuadros.
Today's news have shocked me a lot.
Manuel se quedó a cuadros cuando escuchó el abucheo del público.
Manuel was astonished when the audience booed him.
There is no difference in meaning between "quedarse a cuadros" and "dejar a alguien a cuadros". The difference comes in the context. Because of the use of the reflexive verb "quedarse", when we use the expression quedarse a cuadros, it means that this person is the active subject of the action, meaning that he or she is the one who is astonished or suprised by a fact. If we use dejar a alguien a cuadros, another person or thing is doing the astonished act. In this case, you are still the one being surprised but by the actions of another person. Let's see it in a sentence:
Me quedé a cuadros cuando María me contó que se separaba de su marido.
I was so astonished when Maria told me she was getting divorced.
María dejó a Isabel a cuadros cuando le contó que se separaba de su marido.
Isabel was shocked when Maria told her she was getting divorced.
Remember, though, that this is a colloquial, yet not rude, expression used in informal situations --especially among younger people.
More examples:
Mi madre se quedó a cuadros cuando mi padre le dijo que se iba de vacaciones sin ella.
My mother was so astonished when my father told her that he was going on vacation without her.
Las noticias de hoy me han dejado a cuadros. ¡No entiendo como puede haber tanta violencia en el mundo!
I was so astonished by today's news. I don't understand how can there be so much violence in the world!
¡Belén y Javier van a tener un bebé! ¡Me quedé a cuadros cuando me lo dijeron!
Belen and Javier are going to have a baby! I was shocked when they told me!
Los policías nos dejaron a cuadros cuando nos dijeron quién fue el ladrón. ¡No nos lo esperábamos!
We were so shocked by the police when they told us who the thief was. We didn't expect it!
Me quedé a cuadros cuando escuché la noticia de Michael Jackson. ¡Aún no puedo creer que se haya ido!
I was really shocked when I heard the news about Michael Jackson. I still can't believe he's gone!
Some equivalent expressions in English would be to be surprised, to be astonished or to be shocked.
Las noticias de hoy me han dejado a cuadros.
Today's news have shocked me a lot.
Manuel se quedó a cuadros cuando escuchó el abucheo del público.
Manuel was astonished when the audience booed him.
There is no difference in meaning between "quedarse a cuadros" and "dejar a alguien a cuadros". The difference comes in the context. Because of the use of the reflexive verb "quedarse", when we use the expression quedarse a cuadros, it means that this person is the active subject of the action, meaning that he or she is the one who is astonished or suprised by a fact. If we use dejar a alguien a cuadros, another person or thing is doing the astonished act. In this case, you are still the one being surprised but by the actions of another person. Let's see it in a sentence:
Me quedé a cuadros cuando María me contó que se separaba de su marido.
I was so astonished when Maria told me she was getting divorced.
María dejó a Isabel a cuadros cuando le contó que se separaba de su marido.
Isabel was shocked when Maria told her she was getting divorced.
Remember, though, that this is a colloquial, yet not rude, expression used in informal situations --especially among younger people.
More examples:
Mi madre se quedó a cuadros cuando mi padre le dijo que se iba de vacaciones sin ella.
My mother was so astonished when my father told her that he was going on vacation without her.
Las noticias de hoy me han dejado a cuadros. ¡No entiendo como puede haber tanta violencia en el mundo!
I was so astonished by today's news. I don't understand how can there be so much violence in the world!
¡Belén y Javier van a tener un bebé! ¡Me quedé a cuadros cuando me lo dijeron!
Belen and Javier are going to have a baby! I was shocked when they told me!
Los policías nos dejaron a cuadros cuando nos dijeron quién fue el ladrón. ¡No nos lo esperábamos!
We were so shocked by the police when they told us who the thief was. We didn't expect it!
Me quedé a cuadros cuando escuché la noticia de Michael Jackson. ¡Aún no puedo creer que se haya ido!
I was really shocked when I heard the news about Michael Jackson. I still can't believe he's gone!