Or perhaps I should say "fever hallucinations," since what I experience with a high enough fever is sensory rather than narrative. Each sensation slips away if I focus on it, but returns when I don't. No, they don't make any sense--they must be some random connections in the brain that light up when things get too hot. It's been this way for as long as I can remember.
One is the sensation on the palm or tongue of a steady thin smooth stream of water, such as you get when you turn the faucet on to just barely above the drip stage. Another is the ghostly feeling of a thin rod on the hand: ghostly because it is only the superficial nerves and not the deep ones. The last needs a bit of explaining. With eyes closed, I normally have the sense that there's something like a red dome before me, near on the sides and moderately farther away right in front. In a high fever, the area right at the front of vision is the point of a cone that falls away on the sides to disconcerting (almost terrifying) distance.