Double Dip is one of the four lifelines available to contestants on Who Wants to Be a Millionaire. Double Dip can be used at any point during the game, and is most helpful when the contestant can narrow the correct answer down to one of two choices.
Double Dip lets a contestant choose two different answers to a question. As soon as this lifeline is chosen, the clock stops and the contestant must then provide his first answer. If this answer is correct, the contestant reaches the next level in the game, and game play resumes as usual.
If the first choice is incorrect, the clock resumes and the contestant must choose a second answer before time runs out. As in regular game play, an incorrect answer means that contestants' game is done, while a correct answer means the game can continue.
As of the 2010-2011 season, Double Dip has been retired from the game.
A perfect example of the Double Dip lifeline being used well occurred during the 10th anniversary prime time event, when Regis Philbin took the hot seat to play for charity. Knowing for certain that two answers were incorrect, Philbin used the Double Dip to try the answers he was unsure of, and won the cash for his charity.