We were doing kokyu ho to finish of the lesson and I was playing around with tilting my pelvis so that the motion 'comes' from your centre. Anyway, when I tilted a bit too far the old fabric of my pants tore in two, my partner and I were looking at each other checking if it was only fabric or that something else made that noise from under my hips
The pants are very breezy now, but alas unusable on the tatami
