I have used groupon in the past, however recently I was searching through their website on my cell phone. Later I received a statement from my bank that a purchase was made to Groupon. It seemed I placed my phone in my pocket and somehow push the "Buy" button. I immediately contacted Groupo who stated they would not revoke the purchase due to a 2hr window for goods and a final sale with the supplier.
I explained the incident to no avail. Groupon refuse to refund the purchase although they saw the purchase was made on my cell phone and I was willing to show proof from my bank regarding the notification.
BEWARE: The incident of "But Calling" is the norm. It seems purchasing items from Groupon with your buttocks is also possible