That's a good point to consider - it must be hard for a waitress / waiter to swallow that their evening will take a pay cut because their boss has decided to get into social advertising.
"*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.