To flounce is to move in an exaggerated, emphatic way, especially if your movement expresses anger or impatience. A young child who doesn't like what's for dinner might stand up and flounce away from the table.
If you feel you've been misunderstood, you might need to stifle the urge to flounce off in a huff — it's more mature to stay and try to explain yourself. Flounce is also a noun, meaning both the action of flouncing and a ruffle: "I'll make this dress look fancier by sewing a flounce on the bottom." The huffy movement meaning came first, possibly from a Scandinavian source.