In September 2013, when the onion price was skyrocketed. Groupon came up with an innovative idea to sell onions at Rs. 9/- per kg only. Offer went viral on internet in first few minutes of it's launch. Motive behind this campaign was to capture new customers. In calculation part of this document it is shown that how Customer Acquisition Cost (CAC) was drastically reduced and acquired more customer than regular digital marketing campaign.