So many to choose from. My least favs:
Jar-Jar: "Icky-pooey!"
Anakin: "Are you and angel?"/ "You're a funny little boy" (and the entire dialogue that ensues)
Anakin: "Now THIS is pod-racing!"
Kitster: "That's so wizard, Ani."
I don't hate TPM the way others do. But some of the dialogue is just excruciatingly bad.