An acronym from the initial letters of taking without owner’s consent, T.W.O.C. (also TWOC, Twoc, twoc) denotes the offence of taking a car without the owner’s consent, especially for the purpose of joyriding.

This offence is defined as follows under section 12(1) of the Theft Act 1968:

A person shall be guilty of an offence if, without having the consent of the owner or other lawful authority, he takes any conveyance for his own or another’s use or, knowing that any conveyance has been taken without such authority, drives it or allows himself to be carried in or on it.

Many of the early occurrences of T.W.O.C. that I have found indicate that this acronym originally denoted a social phenomenon prevalent in north-eastern England, particularly in County Durham and in Tyneside, a conurbation on the banks of the River Tyne, stretching from Newcastle upon Tyne to the coast.

According to the Oxford English Dictionary (online edition, December 2020), T.W.O.C. originated in police slang. The earliest quotation in this dictionary is from an entry, dated Friday 20^th October 1972, in the notebook of a Durham Constabulary officer:

Arrested, 17 yrs. Suspected T.W.O.C.

Dilys Winn recorded T.W.O.C. in Murder Ink: The Mystery Reader’s Companion (New York: Workman Publishing Company, Inc., 1977):

T.W.O.C. Taking Without Owner’s Consent (spoken as “twock”): unlawfully borrowing a motor vehicle (“I arrested two men for T.W.O.C.”)

The following is from A brush with the law, an article by Sue Hercombe about the British painter and teacher Val Close (born 1949), who was then artist-in-residence with Northumbria Police—article published in The Journal (Newcastle upon Tyne, Tyneside, England) of Wednesday 9^th January 1985:

The initial connections have been rooted in hard fact. Val spent most of her first month with the force simply learning about the various departments and what goes on in them. She spent a few days with scientific aids, visiting the scenes of burglary, talking to people whose homes had been violated.
She went out with the “Twoc” squad—taking without consent—and saw the crime being committed, the arrest being made. She walked the beat with the new-style community policemen, and she sat in a patrol car as it made its rounds of Newcastle city centre at closing time on a Friday night.

T.W.O.C. has been interpreted as an acronym from the initial letters of taken without owner’s consent—as in the following from the Sandwell Evening Mail (West Bromwich, West Midlands, England) of Saturday 26^th September 1987:

Officers from a crime prevention unit at Bromford Lane police station will be holding “Car Clinic 87” on Sunday, October 4 from 9 am to 5 pm, to warn the public of the dangers of leaving vehicles unprotected.
[…]
Chief Insp David Cocker said he hoped the public would attend and learn some tricks from their “car thief.”
Mr TWOC (Taken Without Consent) is a cartoon series which will show people who have been the victims of thieves, how to get into their cars if they have been locked out.
But only a select few will be allowed in on the secrets.
“We don’t want to encourage people,” said Sgt Richardson.

The acronym T.W.O.C. has given rise to the noun TWOCer (also twocer, twoccer, twocker), denoting a person who steals a car, especially for the purpose of joyriding. The earliest occurrence that I have found is from The joyriders who come to grief, by Edward Pilkington, published in The Guardian (London and Manchester, England) of Wednesday 8^th August 1990:

Joyriding used to be associated exclusively with Northern Ireland, where teenagers grabbed-and-smashed cars as a way of proving their mettle. But now it’s catching on in inner-cities all over the UK. Leicester is probably typical. Two thousand cars were taken there in the first three months of this year alone.
More than one in 10 of all crimes committed last year involved theft of cars, the police say, making it one of the fastest growing areas of recorded crime. In official police jargon it is called TWOC—Taking Without Owner’s Consent. TWOCers are almost exclusively male and more than half are under 17.
But nobody really knows how much joyriding goes on. Some cars are never reported stolen, because they are driven overnight and then carefully returned to the same spot from which they were taken.

The noun TWOCer then occurs in an article about car theft, by Shyama Perera, published in The Observer (London, England) of Sunday 17^th February 1991:

They call themselves the TWOC gangs in Tyneside. Boys from eight to 18, tooled up with balaclavas and iron bars, steal, race and smash cars with such obsession that police liken it to drug addiction. The TWOCs, an acronym for Taking Without Owner’s Consent, are now a feature of the area, their cannibalised wrecks forming bizarre sculptures in the recovery garages.
[…]
TWOC is a modern phenomenon, not to be confused with joyriding, which people did in the Sixties and Seventies when they missed the last bus home and nicked a car to get across town. TWOC is big business, and Tyneside its corporate headquarters. […]
[…]
Solicitor John Purves, who has represented hundreds of TWOCers, says: ‘TWOC provides an escape from their humdrum existences. They are thrilled by the speed of these flying machines and the more dangerous it gets, the more excited they become. It’s an addiction. I had a 14-year-old who admitted five TWOCs and asked for 75 others to be taken into consideration. The press call them deathriders; that’s the real thrill.’
Since the death late last year of 10-month-old Richard Hartley, killed when two TWOCers abandoned a moving car to avoid police, community groups have asked the council to install more sleeping policemen. Their living counterparts are unimpressed: ‘We’ve already got them down on some estates and the kids use them as speed ramps. Imagine the buzz of flying off one of those at 90mph.’

The verb twoc and the verbal noun twoccing occur in the television programmes published in several British newspapers on Thursday 3^rd October 1991—for example in:

– the Evening Mail (West Bromwich, West Midlands, England):

8.30 THIS WEEK. Twoccing Up Your Premiums *. Stealing cars is the fastest growing crime in Britain, and insurance companies are raising their premiums by up to 75 per cent as a result. Police and social workers discuss the high price of this latest epidemic, known on the streets as twoccing—Taking Without the Owners [sic] Consent.

– the Evening Post (Reading, Berkshire, England):

8.30 THIS WEEK Twoccing up your Premiums. A report on the problem of joyriding and the substantial increases on premiums that insurance companies will be imposing on cars likely to be ‘twocced’—taken without the owner’s consent.

* Twoccing Up Your Premiums was the title of an episode of This Week, a British weekly current-affairs television programme produced by Thames Television.

Two synonyms of T.W.O.C., T.A.W.O.C. (i.e., taking away without owner’s consent) and T.D.A. (i.e., taking and driving away), occur in David Rowan presents the Excessively Distorted Language Awards for 1993, published in The Guardian (London and Manchester, England) of Friday 31^st December 1993:

Seriously Lost In Translation Award
[…]
WINNER: the 43 police forces of England and Wales for making it so difficult for linguists to develop the Franglais that Anglo-French channel-tunnel cops will be using. They found that even among the Anglos there are excessive regional differences. Southerners talk of car crimes as TDAs (for taking and driving away); Londoners call them TAWOCs (taking away without owner’s consent), and Geordies TWOCs (taking without owner’s consent). And, as one newspaper pointed out, Thames Valley police refer to drunks in charge of cars as DICs. Which leads to a certain confusion if DICs are seen coming up the ring-road.