Green’s Dictionary of Slang

1. to suspect.

1896		J.F. Lillard Poker Stories 53: The Captain got on to the scheme.
1901		J. Flynt World of Graft 92: I was livin’ with my old woman at the time, but she never got on to me.
1911		E. Dyson ‘Nicholas Don and the Meek Almira’ in Benno and Some of the Push 24: ‘Wait till the little tom from the pie plant gets onter these goin’s on false one!’.
1925		Wodehouse Carry on, Jeeves 31: We want you to suggest some way by which Mr Worple can make Miss Singer’s acquaintance without getting on to the fact that Mr Corcoran already knows her.
1952		W.R. Burnett Little Men, Big World 120: I got to call a halt, Arky. [...] Too many people are getting on to it.

2. (US) to understand, to work out.

1880		Chicago Inter-Ocean 2 June 6/3: Providence registered her second defeat for the Buckeye blue-legs this afternoon, the visitors taking kindly to Ward’s curves, Dunlap and McCormick especially getting on to him in fine style [DA].
1896		Ade Artie (1963) 95: You live here in town awhile and you’ll get on to them people.
1910		Wodehouse Psmith in the City (1993) 117: Psmith acknowledged [...] that possibly Shakespeare had got on to it first.
1913		Van Loan ‘For Revenue Only’ in Lucky Seventh (2004) 208: They’ll get onto that old, round-house wallop of his.
1925		Wodehouse Carry on, Jeeves 30: Muriel Singer was one of those very quiet, appealing girls who have a way of looking at you with their big eyes as if they thought you were the greatest thing on earth and wondered that you hadn’t got on to it yet yourself.
1929		E. Dahlberg Bottom Dogs 12: Tisha didn’t get on to it and thought Lorry was trying to get her nannygoat.
1932		W.R. Burnett Giant Swing 37: ‘I’m all upset today. Got a date and have to stick around till the new girl gets on to it [i.e. a menu]’.
1940		Indiana Gaz. (PA) 11 Sept. 3/1: He said that after he got onto himself, he stopped shooting off his bazoo about his tolerance.

3. to look (at), to observe.

1893		S. Crane Maggie, a Girl of the Streets (2001) 39: Git onto deh mug on deh blokie.
1903		A.H. Lewis Boss 173: Say! get onto that front! That look of not knowin’ nothin’ ought by itself to cash in for half a million!
1908		E. Dyson ‘Two Battlers and a Bear’ in Lone Hand (Sydney) Feb. 377/2: ‘Hi, Genle Annie [...] jist get on to his jills!’.
1913		J. London Valley of the Moon (1914) 39: Get onto yourself, Bert. We got to get outa this. We can’t fight an army.
1965		W. Dick Bunch of Ratbags 135: Get onta me haircut, dad, it’s the latest.

4. to interrogate, to pressurize.

1903		Bulletin (Sydney) 3 Sept. 36/2: I got on to her once quietly about flirting with other fellows, but she said he had to treat us all alike when she was behind the bar or she’d lose her place.
1958		A. Sillitoe Sat. Night and Sun. Morning 131: All right, I will have a fag. I’d better not let mam see me though, or she’ll get on to me.

5. to attack verbally, to criticize.

1911

E. Dyson ‘An Amorous Boy’ in Benno and Some of the Push 179: You’re always getting on to me. Everybody gets on to me. I wish I was dead!

6. (Aus.) to join in, to participate.

1981		A. Weller Day of the Dog 10: Get on to ’er, Dougo. Ya got the ’ole back seat for yaself.
1986		R.G. Barrett Godson 121: ‘There’s a couple of poofs over there keep trying to get on to me’.