Green’s Dictionary of Slang

to study hard, to learn, to memorize, esp. a specific lesson for a specific test or examination; thus mugging up, studying hard.

1845		Gloucester Citizen 11 Jan. 7/2: There are [...] a number of well-dressed and plausible scoundrels who, [...] ‘mugged up’ from works of reference, prey upon the affluent.
1854		Delhi Sketch Bk 1 Aug. 92: [cartoon caption] An Illustration of Ensign Pumpkin’s Lucid Notions ypon Military Law after Mugging for the Inspection.
1860		Hotten Dict. of Modern Sl. etc. (2nd edn) 177: Mug-up [...] To ‘cram’ for an examination. ? Army.
1861		Hills & Plains I 43: [T]hey were not lie other fellows ‘mugging up’ languages and ‘sucking’ far and wide for staff appointments.
1866		Mansfield School-Life at Winchester College (1870) 122: The Praefects would subside into comfortably stuffed seats between their scobs, and set to work ‘Mugging,’ (reading hard).
1870		Hotten Sl. Dict.
1889		G. Allen Tents of Shem II 122: Not clever, Iris corrected; only well read. I’ve mugged it up out of books.
1890		Kipling ‘The Story of the Gadbsys’ in Soldiers Three (1907) 159: I’ve been mugging up that beastly drill.
1900		Bulletin (Sydney) 29 Sept. 13/1: Old Carr believed in his new-found mate for a long time, till he found out that ‘Bouverie-Smith,’ who edits an alleged comic paper in the Strand, had been ‘mugging up’ an old paper of Carr’s sent some time previously to the R.G.S.
1913		A. Lunn Harrovians 24: What was the point of mugging up all this dull stuff?
1937		A. Christie Murder in the Mews (1954) 114: She mugs up historical stuff for writers.
1940		E. Curry Hysterical Hist. of Aus. 1: I could mug up the subject (like a University student).
1940		M. Marples Public School Slang 123: mug [...] (1) to work hard, swot [...] one who mugs being a mugster. This is akin to the more general colloquial use of mug up.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 199: ‘Swotting’ or ‘mugging up’ is only considered good form if a person is on the point of taking an exam.
1971		M. Novotny Kings Road 192: I’m not going to Africa to mug up on Black Art.
1980		(con. 1940s) O. Manning Sum of Things 442: I was never keen on mugging up school books.
2000		Indep. Rev. 22 Jan. 20: I can’t really mug up on any questions.
2024		J. Meades Empty Wigs (t/s) 775: I remembered the names... all the names [...] I mugged up on them.