Don’t get all huffy, or offended or irritated, just because you didn’t know this definition. Like the wolf who huffed and puffed, anyone who’s huffy is easily upset.
If everything you say to your sister seems to make her mad or hurt her feelings, you could say, "Stop being so huffy!" A huffy person might blow the hair off her forehead and stomp away. Don’t get mad, but Huffy is also the brand name of a cool bicycle. This adjective has been around since the 1600s, from huff, which first meant "exhale," and later "bluster with indignation."