Her blouse opens

Sandry was so relieved to be able to turn her backside on the class that she allowed herself to relax slightly, taking a deep breath to try and subdue her red face.

POP! POP! POP! POP!

Like a brief burst of machine gun fire, small white buttons flew from Sandry's front, nearly taking out eyes in the front row. She looked down, horrified, to where her impressive D-cup breasts, barely contained by a white cotton bra, were protruding through the ruined front of her blouse.

"Eek!" Sandry quickly crossed her arms over her chest, but now she had holes torn in her uniform front and back, each too big to hide.