You all know what dim sum is, right? The original dim sum houses originated in Canton, and were a lot like diners: small, roadside establishments that served tea along with a bit of sustenance for weary travelers or rural workers. Just like Spanish tapas, which were originally simple accompaniments to glasses of sherry, these simple Cantonese tea snacks eventually became the main focus of the meal, though tea is, of course, still served. These days, in many parts of Southern mainland China, and in Hong Kong in particular, it's become a weekly ritual family meal, generally taken on weekend mornings.
Food comes served in steam table trolleys stacked high with bamboo or metal steamer baskets. They get pushed around the restaurant from table to table, and diners order by pointing at the dishes they want. Each table gets a card that's stamped with the number of dishes ordered (generally for a couple bucks apiece, though price can vary by dish), and you pay when you leave.
It's tough to find a better way to spend a Sunday morning than a table of friends and family, bottomless tea, lightning-fast (if a little rude) service, and a whole table full of tiny plates crammed with dumplings, steamed buns, and Chinese pastries. That you usually end up paying no more than a few bucks apiece at a dim sum restaurant (no matter how much you order, it seems) helps, of course.