Green’s Dictionary of Slang

1. infatuated, sexually or romantically obsessed (by).

1881		‘Bill Nye’ Bill Nye and Boomerang 192: Ye art the damsel who erst was mashed on Obejoyful.
1889		Kipling ‘Her Little Responsibility’ in Civil & Military Gaz. 19 Sept. (1909) 15: ‘Say, were you ever mashed on a girl? [...] dead, clean gone, head over ears’.
1890		Bird o’ Freedom 8 Jan. 5/3: Our old maid is a regular out and outer. It’s no wonder she’s an old maid, for I’ll swear no one could ever have got mashed on her.
1891		Morton & LeBrunn [perf. Marie Lloyd] Don’t Laugh 🎵 If a nice young curate’s mashed on you. Don't laugh.
1891		H. Lawson ‘The Ghost at the Second Bridge’ in Roderick (1967–9) I 167: ‘She’s mashed,’ said Jack, ‘I do not doubt.’.
1895		Coburg Leader (Vic.) 27 July 1/6: Who was the young man that got mashed on Elsie B. at the party?
1899		A. Binstead Houndsditch Day by Day 60: Young swells who were hopelessly mashed on the serios.
1905		Marvel III:58 30: I never see such a sight! All the girls will go clean mashed on him!
1907		Lone Hand May 15: ‘I never had,’ the sailor swore, / ‘A Queen so mashed on my before!’.
1913		Van Loan ‘The Bachelor Benedict’ in Lucky Seventh (2004) 223: If he got mashed on a girl, it might put him clean out of his stride.
1924		G.H. Lawson Dict. of Aus. Words And Terms 🌐 MASHED — To be in love.
1934		J. Franklyn This Gutter Life 47: If she was mashed on that damn potman, she could have him!
1936		(con. 1830s–60s) ‘Miles Franklin’ All That Swagger 148: I could never make you have me because you were so mashed on Athol Macallister.

2. in a non-sexual context.

1884		Sporting Times 8 Nov. 2/1: We have been to the Cambridge [Music Hall] [...] when we were mashed on the Learned Pig.
1885		C.F. Lummis letter 10 Jan. in Byrkit Letters from the Southwest (1989) 231: He was not the first that got mashed on it [a meerschaum pipe].
1888		‘’Arry at a Radical Reception’ in Punch 12 May 219/1: He is mashed on old Gladstone no end.
1926		Breton & Bevir Adventures of Mrs. May 75: ’Orace [...] would be so sorry to be away, bein’ so mashed on the mission to waifs and strays.