Green’s Dictionary of Slang

1. to apply theatrical make-up.

1859, 1860		Hotten Dict. of Modern Sl. etc.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor III 193/1: Then he underwent the operation of mugging him up with oil-colour paint, black, and not forgetting the lips, red.
1876		C. Hindley Life and Adventures of a Cheap Jack 193: He put on the clown’s dress, got mugged up, and went into the ring.
1882		Chambers’s Journal 19 Aug. 530: My eye! How you do mug up, Charley! You might go through this town [...] and I don’t believe a soul would know you [F&H].
1892		E.J. Milliken ’Arry Ballads 59: You’re mugged up to rights.
1895		C. Crowe Aus. Sl. Dict. 51: Mug Up, to paint and dress, especially with a view to impersonation.

2. in fig. use, to prepare for, to dedicate oneself to.

1889

‘’Arry on Chivalry’ in Punch 20 July 177: But to be a mere moke to the feminines, mugged up to kneel, fetch, and carry?

3. (US black) to put on one’s hat, to leave.

1983

R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].