If a person gets the “last laugh,” then he or she typically achieves something or is otherwise successful in a venture. This phrase in particular is often used to indicate that someone has failed in the past, or has not been the most successful in a particular venture previously. The idea of getting a “last laugh” is based on the idea that each person competing for a certain goal is likely to laugh upon achieving it. In this sense, the person who laughs last is the one who achieves final victory, or who excels over everyone else in completion of a goal.
The origin of the phrase “last laugh” stems from a longer phrase that has appeared in a number of different forms throughout various times. One of the oldest incarnations of the phrase can be found in an English play from about 1607 titled "The Christmas Prince," in which it is said, “He laugheth best that laugheth to the end.” This expression may have been in popular use at the time, but this is among the oldest known records of its use. While it does not use the exact words “last laugh,” this expression has remained in usage and changed over time.
More recent versions of this phrase or idiom typically include more modern phraseology but impart the same basic sentiment. For example, modern expressions include “He laughs best who laughs last” and “He who laughs last, laughs longest.” Both of these expressions are used to indicate the idea that someone who is the last person to laugh, or who has the longest laugh, is somehow the most accomplished or successful. This same concept has been shortened and extended to the simpler noun phrase, “last laugh,” which is typically attributed to someone, such as “He had the last laugh.”
In popular usage, a person who gets the “last laugh” is typically able to succeed despite previous failures, which implies that he or she has been laughed at before. A salesperson, for example, might be part of a major competition to get the most sales within a month in order to win a reward or pay bonus. If that salesperson has been struggling to sell products throughout much of the month, then others could be “laughing” in victory as they sell more goods or earn more money through sales. That salesperson can have the “last laugh,” however, if he or she manages to make a tremendous sale in the last few days of the month, which allows him or her to win the contest.