What are limerick poems?

A limerick is a humorous poem that contains five lines and a rhyming scheme of AABBA. The first, second and fifth lines are between seven and 10 syllables, and the third and fourth lines contain five to seven syllables.

19th century English poet Edward Lear wrote many humorous and nonsensical limericks throughout his career, such as "There was an Old Man of the West" about a man who can't sleep, and "There Was a Young Lady" about a young woman who plays the harp with her chin. Limericks can also be obscene, such as the American poem "There Once was a Man from Nantucket."