Dark Horse:
One who was previously unknown and is now prominent.
Dead Ringer:
100% identical. A duplicate.
Devil's Advocate:
Someone who takes a position for the sake of argument without believing in that particular side of the arguement. It can also mean one who presents a counter argument for a position they do believe in, to another debater.
Don't count your chickens before they hatch:
Don't rely on it until your sure of it.
Don't Look A Gift Horse In The Mouth:
When someone gives you a gift, don't be ungrateful.
Don't Put All Your Eggs In One Basket:
Do not put all your resources in one possibility.
Down To The Wire:
Something that ends at the last minute or last few seconds.
Drastic Times Call For Drastic Measures:
When you are extremely desperate you need to take extremely desperate actions.
Drink like a fish:
To drink very heavily.
Drive someone up the wall:
To irritate and/or annoy very much.
Dropping Like Flies:
A large number of people either falling ill or dying.
