Green’s Dictionary of Slang

aggro n.

also agro
[abbr. SE aggravation + -o sfx (6)]

1. problems, trouble.

[UK]M. Harris The Dilly Boys 95: A few of the boys [...] had boasted with some of the others at the number of boys they could gather and rely on in case of ‘aggro’ (trouble).
[Aus]B. Humphries Traveller’s Tool 45: She’s never given me much aggro in all our married life.
[UK]M. Frayn Now You Know 277: Sorry about the aggro I was giving you earlier.
[UK]K. Waterhouse Soho 44: He’s the one that’s doing all the aggro.
[UK]T. Black Gutted 42: Hod took the cig off me, stubbed it. ‘You don’t need any more aggro’.

2. violence, typically as enjoyed by skinheads, esp. at football matches, beating up Asians etc.

[UK]Oz 22 in Hudson Lang. Teenage Revolution (1983) 3: After some agro, they were let free.
[UK]S. Berkoff East in Decadence and Other Plays (1985) 59: On the streets a victim of nuclear aggro.
[UK]A. Higgins ‘The Bird I Fancied’ Helsingør Station and Other Departures 202: But no Barnet skinheads were aboard, setting out for a night of wog-bashing aggro.
[UK]N. Cohn Yes We Have No 173: Nothing life-threatening, just aggro and name-calling.
[UK]N. Barlay Hooky Gear 228: You ever go to a Cat C fixture back in the heady days of aggro? Saturday afternoon on the turnstiles?
[UK](con. 1980s) I. Welsh Skagboys 14: Them fookin small shields [...] they’re for aggro, not fookin defendin their sen!

3. an aggressive attitude.

[UK]Times 5 May 9: The styling [...] is more sophisticated, more gentle [...] Afro with no aggro, you could say.
[UK]J. McClure Spike Island (1981) 318: This aggro against the policewomen has lifted an awful lot.
[Aus]M. Walker How to Kiss a Crocodile 95: ‘McEnroe’s my idol. He’s got so much aggro in him!’.
[Aus]S. Geason Shaved Fish 5: He smelt of grog and aggro.
[UK]Daily Express 20 May 49: In-your-face-aggro (’I’m selling myself. So what?’ she once countered, when asked why she posed naked).
[UK]G. Malkani Londonstani (2007) 28: Peeps like Kavi n Davinder [...] shud save up their aggro 4 Paki-bashers.

4. any form of problems, difficulties, harassment.

[UK]P. Fordham Inside the Und. 185: They do it on purpose to aggravate you [...] Just aggro.
[UK]S. Gee Never in My Lifetime in Best Radio Plays (1984) 70: Reckon you could handle the aggro?

In phrases

go aggro (v.)

(US campus) to become aggressive.

[US]P. Munro Sl. U. 93: Dude, don’t go aggro on me.