Perhaps frightened by the acres of empty seats at San Diego’s Petco Park this week, the Giants are selling half-price tickets to some of next week’s homestand through the Travelzoo website. Click this link: http://sanfrancisco.giants.mlb.com/sf/ticketing/supergroup.jsp?group=travelzoo and enter the coupon code MAY to get the discount on games of May 25, 26, 27, and 29 — including the day game on Monday, May 25, Memorial Day. However, they add their fees onto the order, so check the total before you pay.