I'm embarrassed to say that I stole an ebay package of Sprite cranberry.
Alright, but what made you steal a package of Sprite?
I was very thirsty for this particular flavor
Theft is theft no matter how small the amount is. You are selfish and impulsive for stealing someone's package that they were anticipating. You ruined someone day and wasted their money because you have no self restraint.
I will return the package, once I'm done drinking it all
I think returning it once you've drunk it all would be adding insult to injury. If you want to make it up to them you could buy a new package and leave it for them, in order to atone for your theft.