A limerick is a short, often humorous, 5 line poem with a certain rhyme scheme (AABBA). It is mainly a poem of jokes and filled with very punny lines. The form of poetry can be found in the early 1800s and was made widely popular by Edward Lear in the early 19th century.
The limerick packs laughs anatomical
Into space that is quite economical.
But the good ones I've seen
So seldom are clean
And the clean ones so seldom are comical