In a money line wager, taking the underdog is also known as "taking the price." For example, "I will take the price on the New York Giants at +200."
In the above example, the player could bet $100 and win $200 if the Giants win the game because a +200 money line is equal to 2:1 odds. If the Giants lose the game, the player would only be out their original $100 investment. The phrase is related to "taking the points," which is when a player bets on an underdog in a point spread event. Whenever a bettor is "taking" something, they are usually betting on the underdog. Betting on the underdog and taking the price is a good strategy when the line is wider than it needs to be. The larger the betting line, the better chance the underdog has of covering it. If lots of action begins falling on one team in a wide open line, the line will begin to shift to close the gap.