It can't be happening. But it is.
Like a line of ballerinas, the boys raise up on their toes and teeter unsteadily. As they shift back and forth to keep their balance, their shoes fall off, and they note to their horror that they no longer have feet.
No, the shoes did not fall off their FEET, as what they have can no longer be fairly described as feet. They fell off hooves, which is what the boys now find to be at the end of their legs. The boys now try to keep balance on their new hooves, but it is difficult. They rock back and forth, until one falls forward. leaning heavily against the wall. But he doesn't stop there. He slides down and down until he rests, curiously more comfortable, on all fours. He sighs in relief as the others stare at him in horror.
No matter. They will all join him soon in his new posture. It will seem as comfortable to them as their former bipedal custom. But for now, it still seems strange to all but to the one who finds himself contentedly - and more stably - on all fours.