From Halopedia, the Halo wiki
Nicothiotal, abbreviated as NTL, is a toxic central nervous system depressant considered to be a quick-acting form of Babble Juice. When imbibed, its outward effects resemble intoxication. Overdosing on the agent can leave the subject in a state of permanent hallucination whereby their mind becomes unable to separate the present reality from memory or dreams. Nicothiotal is a favorite of the Office of Naval Intelligence and other intelligence services because of its short onset of action and because someone poisoned with it can simply appear to be inebriated.
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