Green’s Dictionary of Slang

twig v.1

[? SE tweak or twitch]

1. of a man, to have sexual intercourse [SE twig, to do something vigorously].

[UK]‘Second Libel of Oxford’ in May & Bryson Verse Libel 374: But sure the old boare he hath twigg’d / A sow or two.

2. to disengage, to break off.

[UK]New Canting Dict. n.p.: To Twig, to disingage, to sunder, to snap, to break off.
[UK]Bailey Universal Etym. Eng. Dict. [as cit. 1725].
[UK]B.M. Carew Life and Adventures.
[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: Twig, [...] to disengage, snap asunder, or break off. To twig the darbies; to knock off the irons.
[UK]Lex. Balatronicum [as cit. 1785].
[UK]Farmer & Henley Sl. and Its Analogues.

3. (UK Und.) to hit.

[UK]H. Smith Gale Middleton 1 158: Damn the leary cove! the wind isn’t out of him yet. Twig him another crack, Jem!

In phrases

twig the heel (v.)

(US) to seduce.

[US]Wkly Rake (NY) 18 June n.p.: the rake advises [...] The man who says he will ‘twig the heel’ of a respectable and pretty girl in Cannon street to beware of a cowhiding from A.H .