Happy hours come in many shapes and sizes. At Freeziac (six Twin Cities locations, including 4105 Vinewood Lane N., Plymouth, 763-383-0300, www.freeziac.com), the price-per-ounce of frozen yogurt drops from 45 cents to 29 cents, Monday through Thursday from 9 to 10 p.m. Then there's Cool Cups (120 S. 6th St., Mpls., 612-333-3982, www.coolcupsyogurt.com). Weekdays from 3 to 4:30 p.m., the skyway-level shop cuts the price on all eight flavors of its serve-yourself fro-yo by 10 percent.