Answer:
I saw an ol' gnome
Take a gknock at a gnat
Who was gnibbling the gnose of his gnu.
I said, "Gnasty gnome,
Gnow, stop doing that.
That gnat ain't done gnothing to you."
He gnodded his gnarled ol' head and said,
"'Til gnow I gnever gnew
That gknocking a gnat
In the gnoodle like that
Was gnot a gnice thing to do."
Explanation:
Those are called Alliteration Poems.