Inspired by the style of Uel Aramchek's incredible writing at North of Reality.
"So why do you want them again? I'm just curious, you know, we don't really get very many orders for them."
The customer paused, unsure what to say. "My girlfriend asked me to pick up a few...we're hosting a party and she said they'd be perfect for the mood."
"Well, can't argue there I guess." The shopkeeper lifted his elbows from the desk and turned, walking down an aisle. "It's a little surprising we don't move more of them, either, considering they're the same price as the standards. We had a lighting and visual effects company that we supplied for a while, but..." He paused. "They just sort of disappeared after a while."
"Do they really work?"
Walking back with a few boxes in his hands, the shopkeeper let out a short but hearty guffaw. "Of course they do! There are no falsely advertised products sold at Key Street Hardware!"
The man seemed reassured on none but the surface level. "Surely. I didn't mean to insult you, I just--it doesn't make--you can understand why I'm puzzled, can't you?"
"Oh yes, yes, don't worry. Though we don't get many orders for them, we do get some, and your reaction is not at all atypical. Come over here, I'm happy to give you a demo." Approaching one of the floor lamps the shop had on display, he uncased from one of the boxes a lightbulb. Though shaped as was to be expected, the bulb seemed ever so slightly different from its peers. No filament was visible directly--only a refraction of the filament through the side curves of the bulb. The background behind the bulb, too, was distorted, but not in any familiar way. Brushing a few stray threads of styrofoam from its soft, almost imperceptible glass, he screwed it carefully into a socket on the floor lamp.
"Ready?" The customer nodded, and the shopkeeper flipped the lamp's switch. And suddenly, the room became much...darker. The windows of the building were just as bright, and were clearly letting the same amount of light in--in fact, the lamp itself was illuminated by sunlight--but it was as if the bulb was emitting a shadow. Though still in plain view of a sunbeam, as the customer moved his hand toward the lamp, it became more and more enveloped in shadow until, a few inches from the bulb itself, it could no longer be seen.
The expression of amazement on his face triggered a small laugh from the shopkeeper. "As I said, a not-atypical reaction".
"But how does this work?"
"It all operates within the laws of physics, really. You know how certain gases, such as oxygen, react with fire and act as a fuel?" The customer nodded. "Normal bulbs are usually filled with inert gas--argon, for instance--so that the filament glows instead of starting a fire." The customer again nodded. "But since there are gaseous elements that spur on heat to fire, and those that do not interact with it, must it not follow that there may be those which do the opposite, and catalyze an endothermic reaction?" One more time, but with much less conviction, the customer bobbed his head, then spoke in an uncertain voice.
"Surely this must use an abnormal amount of energy, though--it's actively removing energy from its surrounding environment. Where does that energy go? What about the energy used to remove it?"
Once more the shopkeeper laughed. "I assume you're displeased with your monthly electrical payment?"
"Yes I am, that's why I'm asking! How much more am I going to have to dish out this month because I'm using--"
"Trust me, just keep the bulbs on for a reasonable amount of time. You might be rather pleased with this month's bill."