For people who are serious about table tennis, we suggest you report immediately to AMD Trading Company. This largely undiscovered table-tennis learning center and store features two tables (which can be reserved for $3 per person per hour) and all the latest equipment, including ball-feeding robots. The newest version of one such robot, the TW2700-08, uses double-spin technology (whatever the heck that is) to feed you serves with topspin, underspin, sidespin, or no spin. AMD is hugely popular with the North Beach after-school crowd, which means you can stop by to witness kids as young as six holding their paddles in strange ways and slamming it. If this inspires you, lessons from the owner, Amanda Ho, will run you only $35 an hour. Or, at $6 for 30 minutes, you can borrow that crazy robot.