Lying down is ok. Lying down on McDonald’s counter is not.
That’s what planking is all about – you lie down straight as a wooden plank where no one would. Where no one could.
Sometimes it takes real physical strengh and moral flexibility.
For time to time, accidents happen, so I would recommend some really thorugh consideration before doing anything similar.
But still, accidents happen with sponges, or, I don’t know, ice-cream. You better stay alert all the time!