I found all of the following passage disguised as a coffee stain on page 200 of my copy of Harry Potter and the Goblet of Fire. I'm sure you'll all agree that it really does highlight Voldemort's obsession with unnecessary complication ...
"I'm going to bed," said Harry shortly. "See you in the morning."
Upstairs in the dormitory, he pulled on his pyjamas and got into his four-poster, feeling more tired than he'd ever thought possible. ... He fell asleep almost straightaway and it seemed only seconds later that he was awoken by a strange rumbling noise. It was coming from downstairs, and the man in the bed across the room was making bleary half-awake groaning sounds. Who was the man? Harry moved closer, wishing there were more light in the room, not stopping to wonder where the dormitory and its occupants had gone. As if reading Harry's mind, the man lit an oil-lamp beside his bed. Harry recoiled instantly. Wormtail! He must be in Voldemort's house! Torn between the desire to wake up as soon as he could, and curiosity to know what was causing the deep growling sounds, Harry drifted silently down the stairs after Wormtail.
Wormtail had just reached the living room door when the bone-rattling roaring stopped, to be replaced with a weird rhythmical clattering noise. Harry watched in astonishment as Wormtail heaved a sigh, took a deep breath, and fell sobbing into the room, begging for mercy from his master.
Voldemort suspended his spoon rendition of Oh I Do Like To Be Beside The Seaside long enough to say, in a surprisingly deep voice, "What did you do to my snake venom?"
Harry almost choked. What was going on?
"My lord?!" squeaked Wormtail, spasming from one yoga pose to another.
"Listen to my voice!" Voldemort snarled. "It's dropped at least five octaves since I had my bedtime venom. I can only assume that you omitted the distillation procedure."
"I ... was tired, master," moaned Wormtail, in the bird's nest position.
Voldemort rumbled with annoyance, and brandished his spoons menacingly at Wormtail. "Remember that I have the means to send you to sleep ... permanently."
Harry frowned -- spoons? What was going on?
"Yes, my Lord, of course," said Wormtail, hauling himself upright. "Well," he continued, hopefully, "I'll be off up to bed again, then."
"No, Wormtail, you will not," said Voldemort, with finality. "My voice sounds like the kind that Muggles use to present their -- what do they call them -- tractors --"
"Trailers, my Lord," interrupted Wormtail.
"-- and I will not remain like this any longer than I have to!" Voldemort shouted over Wormtail, his tiny red scaly baby body jumping around in the armchair like some freshly boiled and roasted marionette.
"What would you have me do, master?" asked Wormtail resignedly.
"I want my old voice back, you fool!" bellowed Voldemort, bouncing out of his chair and onto the hearthrug, where he proceeded to flail his tiny limbs as agressively as he could. "I am not strong enough to maintain two complicated spells at once, and you don't have enough skill to undo the damage you have wrought this evening, so ..."
He hesitated.
"Yes, master?" said Wormtail.
Voldemort, visibly making an effort to calm himself down, said, "So we will have to use a ... non-magical solution. I shall need some balloons."
"My Lord?"
"Helium."
Harry woke up with a start. Ron and Seamus must have come up whilst he was asleep, and were now snoring heavily. No sign of Neville yet, though. He looked at Ron and wondered whether he should tell him that Scabbers was about to go find some balloons for Voldemort. Ron would probably think he was drawing attention to himself again, and he would definitely do that idiotic flinch when Harry said Voldemort's name. No. Ron didn't deserve to know anything about Peter, after the thing's he'd been saying.
Harry rolled over in bed, his back to Ron's snores, and thought about what he'd just witnessed. Wormtail should have stomped on his master when he had the chance ... but instead he was wrapping Voldemort up in a dirty old towel, fussing about making sure the ends were all tucked in. Harry nervously backed up against the windowsill, propping his elbow next to a dead plant in a flowerpot.
"There you go, my Lord," said Wormtail. "You're snug as a bug in a rug!"
"Don't forget that I have my spoons in here with me," said Voldemort, his rich bass tones slightly muffled by the tea-stained cloth that covered half his face. "Did you find the bicycle?"
"Yes, master. I had to do a quick Reparo job on the back wheel --"
"Don't brag, Wormtail."
"-- but, other than that, it's as good as new. Shall I just pop you in the basket?" Wormtail's voice was shaking. At first Harry thought this was because of fear, but then he noticed the broad grin that kept breaking across Wormtail's voice whenever he looked away from Voldemort. WHAT WAS GOING ON?
"Yes," replied Voldemort. "Oh, and, since we're going into the village anyway, you might as well take that video back."
"Yes, master," said Wormtail, ejecting Oklahoma from the video recorder. "And you're absolutely sure that there's a helium balloon shop in Little Hangleton?"
"How many times are you going to ask me this, Wormtail?" said Voldemort, his little head shaking with anger inside the folds of the towel. "I have said that there is, and that should be enough! It's next door to the video shop!"
"I think we're all ready now," said Wormtail, seemingly ignoring his master's remarks.
"You are not showing enough remorse," said Voldemort. "Five octaves! Easily five octaves! I could never sing Oh What A Beautiful Morning before, and now it's easy!"
"I am truly sorry, my Lord," said Wormtail, carrying his tiny master toward the back door. "And I don't believe I know that song ... ?"
"Of course you do!" roared Voldemort. "You just saw the film last night!"
He rolled his eyes in exasperation. Harry could see, through all the open doors, Wormtail settling Voldemort into the front basket of a rickety old bicycle on the back step.
"How does it go, master?" asked Wormtail, his shoulders shaking again.
"Well ... it starts off with a lot of nonsense about 'bright golden hazes' and so forth, and then the chorus starts with 'Oh what a beautiful MOOOOORNing ... ' Surely you can remember it now?"
Their voices were growing dimmer as they rode off. Harry could just hear Wormtail replying, "Sorry -- could you sing a little more?" and then Voldemort's rich fruity voice singing into the night, "'I got a wonderful FEEEEELing ... '"
Harry had no idea what had just happened, and he couldn't work out how to wake himself up. He turned to peer through the window, trying to gauge how far Wormtail had gotten. Could he catch up with them? He'd kind of assumed that he'd wake up when Voldemort left the house. He turned back into the room again, and his elbow knocked the plant pot on the windowsill. The once-dead plant was bloomingly alive again. Huh? This dream was stupid! Why couldn't he wake up? He drifted toward the back door and ... Neville was shaking him.
"Harry!" he said urgently.
"What? What is it?" asked Harry, grabbing Neville's arm. "Was I screaming? Did I call out anyone's name? Did you write any of it down?"
"No, Harry," said Neville. "It's time for breakfast."