Let’s be frank right from the start: Couples Retreat is the kind of movie you can appreciate and enjoy when you’re sitting in the drive-thru at McDonald’s wondering what one dollar Redbox rental will go nicely with your Double Quarter Pounder, pound of fries and cattle trough-sized soda. It’s not a terrible show and has a few funny bits, but its best digested with no expectations, and also while inebriated with sugar and cholesterol. The tragedy of Couples Retreat is …