Godderel

I met a man, I can’t think where
Who said that he was Tony Blair.
But what was really very odd
He also said that he was God.

[Kyffin Williams, quoted by Derec Llwyd Morgan in Radio 4's Great Lives]

I can’t quite work out why this is funny. It’s not particularly clever or witty, but it just makes you laugh. Something to do with the rhyme possibly.