Coupons have been around for quite some time. Many of us might remember our mothers cutting them out of newspapers before going shopping. But that was so tedious, right? Enter Groupon: a service that sends daily deals straight to your inbox. It became the hot thing back in 2010, and Google tried buying the company for $6 billion (!) that year. Groupon rejected the bid, and in 2012, their stocked plummeted 79 percent. What happened? People grew tired of checking their email inboxes, and businesses stopped posting deals after many of them didn't see an increase of customers.