(historical,US) A box having a small opening in the top through which individuals can (usually for a small amount of money) reach to retrieve an unknown trinket. A common feature of some fairs.
1870, Jeremiah N. Thomas, “Jonadab Cleaver's Experiment; Or, the Last Church Fair at Rutway”, in Sabbath at Home:
Then pointing successively to the lottery-table, grab-box, ring-cake, and cigars, he continued[…]
1906 February 1, “John the Shoeman's Grab Box”, in The Shoe Retailer:
The grab box was on the third floor of his store, and a sales slip was good for one grab.
1909, Jessie A. Kelley, Our Church Fair: A Farcical Entertainment in Two Acts:
I shall have nothing more to do with this fair if we have a grab-box.