It’s a metaphor which basically means tell us something we don’t already know. Usually pertains to a conversation about something related to politics or religion but could mean anything . In church there’s always a preacher every Sunday. The choir boys and girls are the people who sing the melodies. So basically the choir has heard everything the preacher has to say every Sunday. Does newcomers would not have heard what the preacher had said. So when somebody says preach to the choir the metaphor actually means that the choir has already heard everything the preacher has to say. So if somebody’s rambling on and on about a subject that you already know about and agree with you could say well you’re preaching to the choir LOL get it?

To tell the truth.

The act of two homosexual men rubbing their nipples on one another, one of the males (1) then proceeds to drop plants on the ground. While the second male (2) eats the plants from the ground, taking the bait, the other male (1) brutally rapes him. Before ejaculation, the two finish off by praying to their god.

Extolling/defaming a cause to people convinced of it's greatness/horridness. Etymology is obviously from christian church choirs.

(v.) To defame with nitpicked and irrelevant facts. Used mainly by Jamaicans (Preach dem poison)

The sexual favor returned at ryans confessional

Someone who goes around preaching to the unseen crowd. They can be found in quiet places, or if they are bold, in public, speaking to those who are not there, or to those who are hidden. Most preaching sheiks are borderline or full blown schizophrenics, though are not always crazy, as they appear to be.

Preaching sheiks give entertaining speeches and acts to the spirit world which watches them constantly. This may also be their way of praying to God in a very different style and manner.
if you happen to witness a preaching sheik in action, whether by hearing them preach or watching them put on a show to what appears to be nobody, keep in mind that you might be just the audience they are looking for.
Though alcohol and/or drugs may be involved in the sheik's sermon, they can do it completely sober. They simply choose to exercise their ability to talk outloud when and where they feel comfortable.