"Willie said, 'I'll get you and me something to drink.'"
Here's why:
* "I'll" is the contraction of "I will," which is the correct way to express future tense.
* "Get" is the correct word to use in this context.
* "You and me" is the correct way to order the pronouns in this sentence.
* "Something to drink" is the correct phrase to use for a beverage.
* Quotation marks are necessary to enclose Willie's spoken words.
You can also rephrase the sentence to be more natural-sounding:
"Willie said he'd get us something to drink."