I don’t know how long I was asleep, but all of a sudden there was an awful scream and I was up. There was pap looking wild, and skipping around every which way and yelling about snakes. He said they was crawling up his legs; and then he would give a jump and scream, and say one had bit him on the cheek – but I couldn’t see no snakes. He started and run round and round the cabin, hollering “Take him off! take him off! he’s biting me on the neck!” I never see a man look so wild in the eyes. Pretty soon he was all fagged out, and fell down panting; then he rolled over and over wonderful fast, kicking things every which way, and striking and grabbing at the air with his hands, and screaming and saying there was devils a-hold of him. He wore out by and by, and laid still a while, moaning. Then he laid stiller, and didn’t make a sound. I could hear the owls and the wolves away off in the woods, and it seemed terrible still. He was laying over by the corner. By and by he raised up part way and listened, with his head to one side. He says, very low:

“Tramp – tramp – tramp; that’s the dead; tramp – tramp – tramp; they’re coming after me; but I won’t go. Oh, they’re here! don’t touch me – don’t! hands off – they’re cold; let go. Oh, let a poor devil alone!”

– Mark Twain

The Adventures of Huckleberry Finn, Chapter 6. Pap has gone completely delusional as a result of his alcoholism, believing devils were trying to take hold of him.