I would add that the price point of the Groupon is also important. $20 for $40 worth of good-ass Mediterranean food is a great deal, but every time I've used o

I would add that the price point of the Groupon is also important. $20 for $40 worth of good-ass Mediterranean food is a great deal, but every time I've used one of my three groupons, my date and I have managed to spend something like $60 on the night. So what sounds like a huge margin hit is often smaller. Despite my math background, my behavior is driven by the idea that "I've only used 90% of the groupon amount. Let's have dessert!" So I never spend less than the groupon's value, and instead always spend more.