Some time way back then, we used to say this rhythmic line (spelling out the letters one by one and as here grouped) as a way of remembering how to spell Mississippi:
M I S S/ I S S / I P P/ I - I P P / I S S/ I S S/ I M.
But until a few days ago I wasn't aware of the following variant of the same thing:
M, I, crooked letter, crooked letter, I, crooked letter, crooked letter, I, humpback, humpback, I.
I only became aware of it through reading Crooked Letter, Crooked Letter by Tom Franklin, at the front of which you are told that this is how southern children are taught to spell the name of the state. I recommend the book. Part crime novel, part picture of a small Mississippi community, but mainly the story of two boys, Larry Ott and Silas Jones, one white, the other black, whose boyhood friendship is cruelly sundered, but whose paths again cross in adulthood on account of the key events of which the book tells, it is well-paced and beautifully constructed, and it has what I considered to be a most satisfying ending. The title of Franklin's novel might also be read as signifying two lives which have been knocked out of shape, in part by the racial aspect of the ties and the tensions between them. In any event, it's a really good read.