Up to snuff. Wide awake, knowing, sharp; not easily taken in or imposed upon; alive to scent (Dutch, snuffen, to scent, snuf; Danish, snöfte).
“You'll mar the light by taking it in snuff.”
“Who, ... when it next came there, took it in snuff.” —
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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