STOCKTON, Calif. -- A California family is warning others after they saw something disturbing on their home security camera: a DoorDash driver taking a sip of the milkshake they ordered.Rajesh Malhotra told KTXL his 14-year-old son ordered a cookies and cream milkshake from Cold Stone, but he wasn't the only one who got to enjoy it."(I thought) 'Whoa, that's crazy,'' he said. "I mean, how can someone jeopardize the product like that, especially the food?"The family didn't learn about the incident until the next day -- after Rishab had already finished the frozen treat."My dad told me to check out the video from last night, and once I checked it out I brushed five, six times," Rishab said. "I felt really disgusted."The family said the incident has them thinking twice about using the delivery service again."We have trust between the company and the drivers," Rajesh said. "Once that trust is broken, we can't go back."The family claims they have reached out to the company several times. Two weeks after the incident and they still haven't heard back.