A confession: I am ignorant of the supposed wonders of Costco. There were none around me when I was a kid, and when I moved to NYC, I simply didn't have the room to stock up on a year's supply of toilet paper. SE'rs have raved about the bulk superstore in numerous Talk topics, proclaiming its high-quality, low-cost food, but my friend Matty Jacobs's annual rooftop cookout made me a believer. More