Natives in a Sleeping Bag

Okay, listen up, because this one is a bit of a stretch for you simple folk. The joke is a pun. When you say "two natives" quickly, it sounds like "Twix." It's a classic dad joke, and you're probably just confused because you were thinking too hard about the actual meaning of "natives" and "sleeping bag" instead of just listening for the sound-alike word. Now go eat a Twix, maybe it will help.