They encourage that prominently in several places, including this message on the actually coupon voucher: "*Remember: Groupon customers tip on the full amount

They encourage that prominently in several places, including this message on the actually coupon voucher: "*Remember: Groupon customers tip on the full amount of the pre-discounted bill (and tip generously). That's why we are the coolest customers out there." I've got no lost love for GroupOn, but this massive pile on/proof by anecdote thing is not a dignified moment for HN.