From William Shirer’s Berlin Diary. This entry was during the German invasion of Poland, shortly after war rationing had been implemented in Germany (to much grumbling among the Germans, Shirer noticed).
BERLIN, September 16 
… An American woman I know bought a tin of sardines today. The grocer insisted on opening the can in the shop. Reason: you can’t hoard tinned food if your grocer opens it first.
We restocked our seven-day car food kits today at Costco, but I was shocked to see that they didn’t have any of the excellent Kirkland canned beef on the shelves. This is disturbing; I’m completely out of that stuff and was intending to stock up over the next couple months.