Sin, when done right, tastes like one of these soft, yeasty, luscious cinnamon buns sticky with creamy caramel, a steal at only $2.50. Chef Bonnie Ruth Ianace makes them only on Saturdays, so that also imbues the buns with an even more illicit cachet. You know you really should be doing something constructive, like cleaning out the garage, but all you want to do is snuggle up with a café au lait and one of these 300-plus calorie babies and stuff your face. Don't wait until Sunday. Not only are there no leftovers, Bonnie Ruth's is closed.