A hale and hearty fellow, the Ghost of Christmas Present shows Scrooge how the other half—or rather the 99%—spend their Christmas holidays.
One pretty ingenious detail about the Ghost of the Present is that it's the youngest member of the Christmas-ghost family. This makes sense of course, because it only exists for a couple of days, unlike the Past and the Yet to Come, which cover years. This youth definitely extends to the personality of the thing; the Ghost of Christmas Present is basically the definition of hail-fellow-well-met. He eats a ton, drinks a ton, laughs, and generally has a blast wherever he goes.
This fits well with his function, too. The memories of old Christmases might be tinged with regret or wistfulness, and the future might be fraught with worry or anxiety, but real-time Christmas is supposed to be all happy and fun and relaxed and joyful.
And, just as we start to get a nice little party on with this ghost, we get another alarming ghost disappearance:
[T]he Ghost grew older, clearly older. […]
"Forgive me if I am not justified in what I ask," said Scrooge, looking intently at the Spirit's robe, "but I see something strange, and not belonging to yourself, protruding from your skirts. Is it a foot or a claw?" […]
From the foldings of its robe, it brought two children; wretched, abject, frightful, hideous, miserable. (3.131-139)
Um, what the what? Just for the record, dudes: the ghost first grows really old… and then gives birth. Birth. Yeah, that is some crazy hallucinatory weirdness right there.
But the best part might just be Scrooge's overly polite reaction. Instead of freaking out, he is worried about getting too personal and wondering if it's not too nosy to ask just what those strange claws coming out from under the ghost's robe might be.
And yet, this response to the ghost's going away is so very different from the first, isn't it? Instead of wrestling him and his emergent claws to the ground, Scrooge is sympathetic and concerned. Is this is a sign of Scrooge changing his ways? Or is this yet another instance of Scrooge clinging to rationalism in the face of the supernatural, like he does with the doorknocker?