Green’s Dictionary of Slang

1. a ragged, disreputable person; a low rascally fellow.

1611		Chapman May-Day II i: If I thought ’twould ever come to that, I’d hire some shag-rag or other for half a cheqeen to cut’s throat.
c.1625		Rowley Woman never Vext 26: Alas poore Shagragge, My Mistris does but gull him.
1649		Man in the Moon 28 May - 5 June 68: Shall [...] the very scummes, offall and shackraggs of of a Common-wealth reigne, rule and Tyrannize over us?
1719		in D’Urfey Pills to Purge Melancholy II 327: Sharks, Shagrags, Shatter-brains, Panders.
1759–67		Sterne Tristram Shandy (1949) 334: There was a good farcical house, large enough to hold – aye – and sublimate them, shag-rag and bob-tail, male and female, all together.
1872		Westmoreland Gaz. 10 Feb. 2/5: John of Antioch he suspected of being a ‘shagrag’.

2. attrib. use of sense 1.

c.1592		Marlowe Jew of Malta IV iv: Was ever Jew tormented as I am? To have a shag-rag knave to come.
1615		Merrie Dialogue Between Band, Cuffe, and Ruffe A: A scurvie shag-ragge Gentleman [...] a Punie, a Freshman, come vp hither to learne fashions.