hands down
1. Also, in a breeze; in a walk. Easily, without effort, as in She won the election hands down, or They won in a breeze, 10-0, or The top players get through the first rounds of the tournament in a walk. All of these expressions originated in sports. Hands down, dating from the mid-1800s, comes from horse racing, where jockeys drop their hands downward and relax their hold when they are sure to win. In a breeze, first recorded in a baseball magazine in 1910, alludes to the rapid and easy passage of moving air; in a walk, also from baseball, alludes to taking a base on balls, that is, reaching first base without having hit a pitched ball because of the pitcher's mistakes.
2. Unquestionably, without a doubt, as in Hands down, it was the best thing I've ever done.