On Saturday Glen Davis  will roll up his sleeves to roll burritos for a group of Celtics  fans at Chipotle Mexican Grill in Cambridge from 3:30-4:30pm. Five WEEI contest winners as well as ten local youth from BELL (Building Educated Leaders for Life) will enjoy lunch courtesy of Big Baby. Davis will also film a promotional video for Chipotle which will air during Celtics home games. All those in attendance will play extras in the video. On Friday the Celtics announced Chipotle Mexican Grill has become an official team partner.