A term used to describe a failure state of lithium-ion batteries, such as those found in smartphones and laptops. A battery can become a spicy pillow due to multiple factors, including (but not limited to) the battery's age, physical damage to the battery, and/or an error in manufacturing or installing the battery. In this state of failure, the battery has entered "thermal runaway": unwanted chemical reactions inside the battery cause heat and poisonous gases to build up inside it.

The "pillow": the build-up of gases inside the battery causes it to swell, resembling a pillow. This often happens slowly over time. The swelling is an obvious sign that the battery has failed, or is about to fail. The pressure build-up may in turn make the battery's device bulge and then come apart, e.g. a phone's screen cracking and/or separating from the phone body.

The "spicy": the swollen battery is now a fire and/or explosion hazard. Improperly-contained spicy pillows have destroyed vast swathes of electronic equipment, set houses ablaze, and sent people to the emergency room with third-degree burns, often due to the phones in their pockets.
"I don't care how fun it looked on YouTube, Dan — don't pop that spicy pillow!"
by cosmogyral-delirium August 10, 2020
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A battery that has puffed up to an expanded state, popularized by r/spicypillows on reddit.
Woah! That's a Spicy Pillow
by SavageSheepYT March 3, 2021
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A battery pack, that due to a build-up of heat and gasses, has swollen into a large fluffy pillow that you should never lay on
She opened her old laptop to find a spicy pillow inside.
by MsFemboy June 5, 2023
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A situation where your sexual partner has eaten Thai or Indian cuisine of a very hot nature Hot meaning spice level not temperature and prior to intercourse sprayed the bedding and pillows with fiery diathermia. The poorly digested food retains it's spice level hence - Spicy Pillow
Last night Pangheet had extra spicy Tandoori goat and jalapeno naan. Just as we began the sexy time he had a gurgling and erupted a fountain of hot liquid feces. My beautiful 700 count sheets are ruined but I love my spicy pillow.
by Robotronic 421 April 26, 2023
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