Q. A fellow came into shul before Chanukah and saw 20 bottles of olive oil on the table with a notice that read: “Each bottle 19 shekels, please put the money in the pushka.” The fellow figured out that the owner stands to make 380 shekels on the sale. He switched the sign for one of his own that read: “Each bottle 20 shekels, please put the money in the pushka.” And took one without paying.

Considering that 20 shekels for that oil is still a great bargain, and the owner will still make 380 shekels, what has the fellow done wrong?

A. An almost exact shailah is to be found in sefer Chashukei Chemed (Baba Metziah 76a), where Horav Silverstein Shlit”a rules that the overpaid money has to be returned to the buyers, even though they willingly paid it. The enterprising fellow is a gazlan, as he took a bottle of oil that he was not entitled to.

Horav Shlomo Miller Shlit”a agrees with this ruling

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a