According to the official Disney World website, outside food and drinks are allowed in the park, but there are some restrictions. You can't bring in any glass containers or alcohol, because, well, safety first, people! And let's be real, you don't want to be that guy who tries to sneak in a six-pack and ends up getting turned away at the gate.
Now, you might be thinking, "But what about my favorite snack?" Well, the good news is that you can bring in your own snacks, like chips or fruit, as long as they're not in a glass container. Just don't try to bring in a full-on picnic, because that's just not cool, dude. Disney World has plenty of food options available, from burgers to ice cream, so you won't go hungry.