laughing jackass: see kookaburra.

laughing gas: see nitrous oxide.

or laughing jackass

Eastern Australian species (Dacelo gigas) of forest kingfisher (subfamily Daceloninae). Its call, which sounds like fiendish laughter, can be heard very early in the morning and just after sunset. A gray-brown, woodland-dwelling bird, it reaches a length of 17 in. (43 cm), with a 3.2–4-in. (8–10-cm) beak. In its native habitat it eats invertebrates and small vertebrates, including venomous snakes. In western Australia and New Zealand, where it has been introduced, it has been known to attack chickens and ducklings.

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or laughing gas

Inorganic compound, one of the oxides of nitrogen. A colourless gas with a pleasantly sweetish odour and taste, it has an analgesic effect when inhaled; it is used as an anesthetic (often called just “gas”) in dentistry and surgery. This effect is preceded by mild hysteria, sometimes with laughter, hence the name laughing gas. It is also used as a propellant in food aerosols and as a leak detector.

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