What does it mean when planking while someone is singing?

Planking is a yoga position where you balance on your toes and forearms while engaging your core by holding your trunk and backside up in the air as flat as a plank of wood and holding the position for an extended period of time. Planking builds the crucial muscles that control most of your body, your core. Not only crucial to balance and propoer posture, it also improves your instrument as a singer. You can sing while planking as an exercise. I suppose planking while someone is singing would be exactly that. You planking while someone else is singing.