To play up means to emphasize or exaggerate something to make it seem more important or dramatic than it really is. When you play up your accomplishments in a story, you make them sound bigger or more impressive. A news article might play up the dangers of a situation to grab readers' attention.

Imagine you got a B+ on a tough science test. If you play up the difficulty, you might tell your parents it was “impossible” and “the hardest test ever,” making your grade sound more impressive. Politicians sometimes play up their opponents' mistakes during campaigns. A movie trailer might play up the scariest scenes to get people excited about seeing the film.

The phrase can also mean to misbehave or cause trouble, especially for children. When kids play up during class, they're being disruptive or not following directions. A child might play up when tired or seeking attention.

Less commonly, play up can mean to flatter someone excessively, trying to win their favor by emphasizing how wonderful they are.

Notice that playing something up isn't quite the same as lying outright. It's more about highlighting certain parts while downplaying others, stretching the truth rather than inventing it completely.