The more negative a world is, the colder Dream feels. However, he's grown so used to it that he almost never starts shivering, even when battling Nightmare. He stops in an Outerswap timeline on a patrol, and he accidentally runs into a monster of that universe.
He's not thrilled, since he knows he's not supposed to intervene. Then, the other monster asks if he's feeling okay.
"Yeah," he answers, shrugging. "Why? You're worried; what is it?"
"Um... well..." they stammer uneasily. "You're shaking. Really, really hard."
Only then, Dream realizes he's been rubbing his arms this whole time, and he holds his trembling hands out in front of him. He laughs nervously and chatters, "Well... I g-guess I am sha-shaking..."
Then he wobbles, and the last thing he registers is that he's falling and everything is so, so cold.