The only Italian one I know I learned in Firenze when I was studying there (it was a while ago so correct me if I make any mistakes!)

Voglio una Coca-cola calda con una canuccia corta corta.
I want a hot coke with a short, short straw.

The funny thing about this tongue-twister is that you have to try to say it in the Florentine dialect. This means that the C's all become pronounced more like H: Voglio una hoha-hola halda hon una hanuccia horta horta!