Green’s Dictionary of Slang

(drugs) nitrous oxide.

1976		Eble Campus Sl. Nov. 6: whippet – an indefinite amount of dinitrous oxide inhaled from a cannister to produce a state of euphoria.
1984		Abel Dict. Drug Abuse Terms.
2001		ONDCP Street Terms 22: Whippets — Nitrous oxide.
2018-20		T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Whippit – nitrous oxide container.