She wants

Gryffindor and Ravenclaw stare at Slytherin for half a second before they burst out laughing, watching the flush on Slytherin's face.

"Told you not to wear something so revealing!" Ravenclaw laughs, drawing more attention towards Slytherin. "What's the matter shirt a little too tight?"

Slytherin's face turns bright red, first from embarrassment and then anger. "You bitch!" she screams, staring straight at Ravenclaw. "You fucking bitch!"

With that she launches herself at Ravenclaw, barrelling into her, the pair of them crashing to the ground beside the queue, and you're pleased to see that Slytherin has forgotten about her shirt, letting it flare open to flash that impressive bust, and her short skirt flaring up as well, giving you a great view of the thin black thong she has on underneath it.