Coffee continues to be the most efficient fuel for the human body's complex system of fuel injectors, auxiliary hearts, and flux capacitors. Fill up your flesh tank with today's Groupon: for $5, you get $10 worth of coffee, sandwiches, and café fare at Boston Common Coffee Co.. Today's deal is valid at all three Boston locations.

The caffeine connoisseurs at Boston Common Coffee Co. roast their own beans at a local facility for optimal freshness, pairing the sleep-shaking sips with a sumptuous spread of energizing eats. The in-house bakers and cooks whip up morning mouthfuls in the form of breakfast sandwiches ($3.23–$4.25), muffin tops ($1.85), and freshly baked bagels and croissants ($1.15+), crafted using local ingredients whenever possible to ensure quality. Sink into the eatery's plush leather couches while sinking teeth into the asparagus strata⎯a quiche-like entree made from bread, asparagus, tomatoes, and cheese ($4.25)—or the sourdough-ensconced Prince panini ($6.75–$6.95), a roasted turkey, cheddar, tomato, and dijon-mustard sandwich whose deliciousness can only be expressed as an unpronounceable symbol. Patrons can also opt to take a slice of the coffee pie home by purchasing Boston Common Coffee's flavored, fair traded, or varietal coffees by the pound ($10.25+).