Here are some possible origins:
* Shortened form of "Susan" or "Suzanne": Sookie could be a nickname for these names.
* Derived from "Sweet": "Sookie" might be a playful alteration of "Sweet" due to its similar sound.
* A fictional name: The character Sookie Stackhouse in the "Southern Vampire Mysteries" book series and HBO's "True Blood" might have popularized the name, though it was likely created for the series.
Without more context, it's difficult to pinpoint the exact meaning of "Sookie."