flounce in
To move into some place or thing in a bouncy or spasmodic manner. That girl flounced in like she owned the place—typical of someone who's underage.
flounce in (to some place)
to move into a place with exaggerated or jerky motions. A couple of teenagers flounced into the store and started examining the most expensive merchandise. They flounced in and caught the eye of the security guard.