Idiom – D

Dark Horse: One who was previously unknown and is now prominent.
Examples: It's difficult to predict who will win the project. There are two or three dark horses in this proposal competition.

Devil's Advocate: someone who pretends in an argument without believing in that particular side of the argument. (Opposite of the God's Advocate)
Example: Just to Play Devil’s Advocate, Why Didn’t Clinton Address Charges About Attacking Women?

Don't count your chickens before they hatch: should not make any plans that depend on something good happening until a good thing has really happened
Example: Don’t count your chickens before they hatch! We haven’t even submitted our proposal yet!

don't give up the day job: not very good at doing something and is not likely ever to be successful at doing it.
Example: What did you think of my thinking? Wom, don't give up the day job!

don't look a gift horse in the mouth: do not complain or refuse if a gift is not perfect; take what you've been given without criticism or emphasis on its worth
Example: It's not the job what we expected but it will pay good money. We should not look a gift horse in the mouth.

don't look a gift horse in the mouth : When someone gives you a gift, don't be ungrateful.
Example: I prefer to wear light colored shirts, but my mom gave me a bunch of dark colored ones; oh well, I shouldn't look a gift horse in the mouth and will try them on later.

Don't put all your eggs in one basket: Do not put all your resources in one possibility.
Example: You have to balance your investment portfolio. Don't put all your eggs in one basket.

Don't teach your grandmother how to suck eggs: a person is giving advice to someone else about a subject of which they are already know more about than you
Example: You're teaching your grandmother how to suck eggs, boy. Your PM has been playing this sort of works since before you were born!

Down to the wire: at the very end of a process or project that it is possible to do something
Example: It was a battle of strength that came down to the wire when we challenged our client to settle down the open issues.

Drink like a fish: drink excessive amounts of alcohol.
Example: Many of my old friends say I was drunk like a fish, but I don't think I have drunk too much, only too often.