Final answer:
The Starbucks social media marketing campaign that let customers personalize a cup with their artwork was called the White Cup Contest.
Step-by-step explanation:
The Starbucks social media marketing campaign that allowed customers to customize a cup with art was called the White Cup Contest.
Launched in April 2014, this campaign encouraged customers to decorate their Starbucks cups with original artwork and share their creations on social media using the hashtag #WhiteCupContest.
This user-generated content approach not only engaged the Starbucks community in a creative exercise but also served as a powerful tool for brand promotion across social networks.