A clerihew is a comic verse form invented by Edmund Clerihew Bentley (1875-1956), consisting of four lines rhyming AABB, but with no regular metre or line length. Some of Bentley's own include:

George the Third
Ought never to have occurred
One can only wonder
At such a blunder

Sir Christopher Wren
Siad 'I am going to dine with some men.
If anyone calls
Say I am designing St. Paul's

John Stuart Mill
By a mighty effort of will
Overcame his natural bonhomie
And wrote 'Principles of Political Economy

The art of Biography
Is different from Geography
Geography is about maps
But Biography is about chaps

This one's not by him:

Of haikus there are many
In this thread they're ten-a-penny
But very few
Attempt to post a clerihew

Wassail! V