booster bag
n.— «Fact is, she may pick up 12 or 15 different articles and put them in her shopping bag or umbrella or her booster bag on one floor and then go on to the next. A booster bag is a store-label dress or suit box with a panel or slot cut in the side. Cotton batten is put in the bottom, just in case the lifter picks up something heavy. It won’t make a clunk when it drops in.» —“Shoplifting Constant Threat to Stores But Detectives Must Be Very Sure!” by Grace Lewis Post-Standard (Syracuse, N.Y.) Aug. 5, 1954. (source: Double-Tongued Dictionary)