Despite being only nine years old, Spike wrestled with the existential problems faced by those many times his age. Why are we here? What is the point of life? Does Goddess exist?
But now, he realized, all those questions had at last been answered definitively. This was heaven. Unlimited ice cream was the answer to all the questions of life. There was no more to ruminate on. There was only ice cream in need of being eaten. This was his simple religion: eat ice cream.
As he made a dent in his third tub of Minty Delight, his blissful trance was shattered by a roaring wind, and before him he saw not future Twilight, but instead his own visage!
"Spike! You gotta stop eating all that ice cream! You're messing with the timeline!"
"Woah, future me! You... don't look much different."
"I'm from next Tuesday."
"Oh. That's kind of a let down."
"Look," Future Spike said, exasperated," you gotta stop eating all that ice cream. If you don't change your ways, you'll eat so much that you'll throw up, and Twilight will have to clean it up, and in doing so she accidentally lights your flammable stomach acid on fire and it burns our house down! You don't want to burn our house down, do you? Twilight's all depressed now, but there's no more ice cream for her to eat, because it all melted! It took me two days to figure out how to do this spell too! That's two days I could have been reading comic books! Think of the comic books, Spike! Think of the comic books!"
"Woah, woah, woah, are you saying I can't eat ice cream? I love Twilight, and I love our home, but I'm not sure that's a choice I can accept!"
"Dude, you can still eat a ton of ice cream. Just stop before you throw up."
"Oh, okay. Thank you, future Spike."
"You're welcome. Live long and prosper, and may you have more success with Rarity than I ever will..."
"Wait, what?!"