Sabes que significa "you are preaching to the choir"?

You are preaching to the choir

This idiom means that you don't have to say more things to another person because she or he already agrees with you.

En español sería algo equivalente a no desperdiciar el tiempo tratando de convencer a alguien que ya está totalmente de acuerdo.

preaching to the choir

Example:

You: I know many governments are corrupted, because ... 

Your friend: Yes buddy, you are preaching to the choir.

Se que muchos gobiernos son corruptos, porque ...

Si amigo, no desperdicies tu tiempo, porque estoy totalmente de acuerdo.

¿Como se dice salir del clóset?

Salir del closet

Salir del armario

To come out of the closet - It means when someone tells their friends, family and everybody that he's a gay.

Example:

Ricky Martin finally came out of the closet, he told the media that he's gay. - Ricky Martin finalmente salió del clóset / armario, el le dijo a los medios que es gay.

¿Sabes cómo decir: A palabras necias, oidos sordos?

Turn a deaf ear to foolish comments

Turn a deaf ear to foolish comments. It means that you take no notice of the stupid things people say. 

Foolish comments - palabras necias
deaf ear - oido sordo.

Example:

You shouldn't get angry at him, he's too drunk. Turn a deaf ear to foolish comments.
No deberías enojarte con el, está muy borracho. A palabras necias, oidos sordos.