This study is trying to investigate the underlying factors of consumer participation to the special promotion strategy. The most representative example of this kind of special promotion is Starbucks Summer Promotion Event. A lot of people are trying to participate to this special promotion event. Why do many people are participating to Starbucks summer promotion and what are the underlying factors of customer engagement. We tried to answer these research questions by using the mixed methodology with quantitative and qualitative study. Especially, we tried to use Python language with LDA (Latent Dirichlet Allocation) technique to analyze Instagram online data. Managerial implications and the limitations of the study were also discussed.