Hobby-horses were a children’s toy consisting of a stick topped with a horse’s head. This toy evolved from original hobby-horses: large horse costumes worn by dancers participating in May Day festivals. In the late 1500s, hobby-horses began to be omitted from festivals, prompting the composition of the ballad which mourns, “For oh, for oh, the hobby-horse is forgot.”  But hobby-horse was also a derogatory term for women who have multiple sexual partners. Bringing up hobby-horses immediately after referring to his mother allows Hamlet to fire another insult at her.