"Red Cup Day" is typically the most profitable day of the year for Starbucks, according to Madelyne Austin, a Houston employee who has worked at the chain store for eight years. While the promotion is popular among coffee drinkers, Austin said Red Cup Day is "horrible" for Starbucks employees. She said the location where she works as a supervisor, at 6400 Fannin St. in the Texas Medical Center, saw record-setting sales during last year's event but also became overcrowded and overwhelmed. Some customers left without their paid-for beverages because they became frustrated with extended wait times. "When I told them what our numbers looked like, she was like, ‘Oh my gosh. Congratulations. You guys are such a success. Thanks so much for your hard work,'" Austin recalled. "That was really upsetting to us, because we don't see that as a success. We were essentially stealing from our customers. We were taking their money through the mobile order app and then they weren't ever getting t...