A chemical compound formally called nitrous oxide. It is a colorless, sweet-tasting gas that is often used as an inexpensive recreational drug to achieve temporary highs. The drug can usually be obtained easily as it is not a controlled substance. Nitrous oxide is legally used by dentists for anesthesia, by manufacturers for pressurising canisters, and accelerating the speed of race cars.

If ingested at high levels, laughing gas can cause death due to lack of oxygen. It can also lead to spasms, convulsions and other health problems. Nitrous oxide is also considered a greenhouse gas and is many times more dangerous to the Earth's ozone layer than carbon dioxide.

Laughing gas has gained popularity as a mainstream drug in recent years, propelled by the ease of social media to reach young people and spread the word.