Interesting question, Tinstaafl. As an atheist, I promised myself that, if called upon to say grace, I would keep it secular. In the event, to my shame, I conformed and chuntered some pious banalities. I am, however, saving this one for the next opportunity:
"Oh gracious (insert name of supermarket or wholesaler here), we thank thee for thy bountiful gifts. Tonight we feast on generous helpings of food that were purchased from your glorious shelves. You graced us with sales on this leg of lamb for us to feast on, and two-for-one specials on frozen prawns. And we will try, in your name, to buy healthy food, so we do not succumb to the evils of the fat demons. For we know if we are wicked and eat too much of the chocolate tort we recieved, we will be under the power of the dastardly PTI for eternity. We must withstand Fat's temptation and defeat him with regular exercise. In (insert name of supermarket or wholesaler here)'s name, dig in."