What is the second-least common method of shipping?
method of shipping refers to method_name; least method refers to Min(Count(method_id))
SELECT T2.method_name FROM cust_order AS T1 INNER JOIN shipping_method AS T2 ON T1.shipping_method_id = T2.method_id GROUP BY T2.method_name ORDER BY COUNT(T2.method_id) ASC LIMIT 1, 1