What's a mulligan? A mulligan is a do-over. A second chance to get something right.
Mulligan was originally a golfing term. Mulligans aren't legal – if you badly blow a golf shot, you're supposed to take the penalty (hitting the next shot from the sand pit or high grass, for example, if your mistake landed you there, or relocating the ball and taking a one-stroke penalty). But in a friendly game of golf with buddies, some people allow a few mulligans.
The word mulligan can be used outside of golf and even outside of sports. In the card games “Magic: the Gathering” or “Pokemon,” in certain situations players can use a mulligan rule to get out of really bad hands or other problems. We can call for a mulligan with friends and family if we make a mistake in our ordinary lives, too.
How can you use a do-over today?
By the way...
Apparently, nobody really knows how the word mulligan got started. Presumably some guy with the last name Mulligan liked to “cheat” at golf and got his friends to go along with it. There are several somebodies linked to the origin of the word—but they can't all be true, so I am content to just not know!