Groupon occasionally offers promotional Bucks (e.g., "$10 in Bucks for your next purchase") for buying specific local deals within a set timeframe.

If your bucks do not cover the full cost, you will be prompted to pay the remaining balance with a credit card. Important Tips and Restrictions

How do I use my Groupon bucks? The purchase ... - JustAnswer

While you cannot directly purchase Groupon Bucks like a gift card, they can be acquired through several methods. How to Get Groupon Bucks