A limerick is a five line witty poem with rhythm. The first, second, and fifth lines are longer lines and rhyme. They should have between seven to ten syllables. The third and fourth lines are shorter and rhyme. They have five to seven syllables. Here is an example:
There once was a man from Blether.
Whose skin looked like dry, old leather.
He spent all his time afloat
On a rickety old boat
That man just loved the sea weather.