A Sneeze, Detention, and Sissy Spacek - S1-E13
Visible crew/equipment: When Sheldon is running away from Mary in the garage, the set lights are reflected in his helmet. (00:18:00)
Visible crew/equipment: When Missy runs through the house at the start the stage lights are reflected in her sunglasses. (00:02:25)
Answer: Mary is highly religious and completely against any form of alcohol as shown in Big Bang Theory numerous times.