The wait for watermelon season is officially over. To celebrate the start of summer, On The Border Mexican Grill & Cantina is serving up its famous Watermelon Margarita for just $4 every Thursday — through August 31. (If you’re really thirsty, sip on a grande-size watermelon margarita for $5.) Combine the deal with its complimentary endless chips and salsa for a truly frugal fiesta. As always, please don’t drink and drive. There are locations in Aurora, Colorado Springs, Golden, Highlands Ranch and Loveland.