What a creepy poem. Since I can't really say it any better, here's a little history for you lifted from Wikipedia.
" 'How Doth the Little Crocodile' is a parody of the moralistic poem 'Against Idleness And Mischief' by Isaac Watts (Alice was originally trying to recite that.) Watts' poem begins 'How doth the little busy bee,' and uses a bee as a model of hard work. In Carroll's parody, the crocodile's corresponding 'virtues' are deception and predation, themes which recur throughout Alice's adventures in both books, and especially in the poems."