tibby drop n.
to take someone unawares.
|Sl. Dict. 321: To drop on one’s tibby is to frighten or startle any one, to take one unawares.|
|‘The Chickaleary Cove’ [lyrics] I’m a Chickaleary bloke, with my vun-two-three — / Vitechapel was the village I was born in; / To catch me on the hop / Or on my tibby drop / You must vake up very early in the mornin’!|
|Appleton’s Journal (N.Y.) 1 May 562: Goodbye johnny, before I leave you, / One more kiss before I go, / For to catch me on the top, / Or on my tibby drop.|