A guy goes to be alone, he winds up in a tree with a kid and approximately ten thousand kittens.

This punchline was missing the joke part, but Sans is chuckling nonetheless.

"Don't worry, you don't gotta be so considerate." Sans winks, nudging Steven gently. "I've gotten asked that question so many times today I think I'd rather you just tell me how you're doin'. Don't leaf me hangin'."