jabbing salute: a player giving the fans "the finger," but in a mock fascist salute
Source: GTH

Jacanory(also spelled Jackanory): rhyming slang for a glib excuse. The unstated rhyming component is "story." From a children's TV show where books were serialised.
Source: Partridge

Jack, to: to quit ( in the building trade).  One dissatisfied construction worker might say to the other, "let's jack it in."
Source: LS3

Jack: a detective. Sly jack: a shop or store detective.
Source: LS2

Jack Sharps: small lake fish, a translation of the Gaelic "kickshawn." The word then was cut down to "Jackie."
Source: Shaw III

Jacks and Ollies: children's game (also known as Fivestones). The stones are the jacks, to be tossed in the air (five of them, one at a time), as the marbles are picked up. In Lancashire the game was played with a marble and the knuckle bones of sheep.
Source: LS1, SHAW III

jacksie(sometimes jaxie): one's rear end
Source: SL

Jam butty car: police patrol car
Jam butty is a jam sandwich, and the allusion is to the red stripe painted on some police cars.
Source: LS3

Jam butty. Bread smeared with jam
Source: LS1, LS2

Jam(rhyming): parole
The rhyme is with jam roll
Source: LS4

jammy: lucky, someone who lands on his feet
Source: ODS, SL

jam rolly polly: treat served at the school canteen
Source: SL

Jangler: a piano
Source: LS2

Jangler-wangler: a pianist or a teacher of the piano.
Source: LS2

jangling: gossiping
Source: LS2

Jankers, to be on: to be put in a stockade or a military jail
Source: Partridge

Janner(also Jenner): a Cornishman, or generally a person from the West Country, usually identifiable by a Devon accent and burr.
Source: DS

Jannock: the real truth
I'm tellin' yer an' that's jannock
Source: LS2

jar: half a pint of beer
Source: LS2

jarks(obsolete): seals
Source: A

Jars out: announcement that beer can be bought on a carry out basis
Shaw says that "jars out" also describes a "do" at which there will be tremendous quantities of beer.
Sources: ML, LS1

Jaspers: cockroaches
Source: LS3

jaws harp: a jew's harp
Source: SL

jaxie(or jacksie): arse, bottom
Source: SL

Jeff': urination
Source: SL

jelly man: a safe breaker
Source: ZCAR

jerkbumpt, to be(obsolete): to be given a sore behind, a hot bottom
Source: A

jerkers, the: piece of playground equipment which the youngsters used to go back and forth on and make slam against a top railing
Source: SL

Jerkyl and Hyde: an obnoxious person of unpredictable temperament
Source: IHBY

Jerry(or jirry): chamber pot
Source: LS

Jerry chandeliers: illumination shells dropped by German bombers during the Liverpool Blitz
Source: LI30

Jesus Fluid: holy water
Source: LS2

Jesus-boots. Purra Jesus-boots. Pair of sandals.
Source: LS1,LS2

jib, to: to buck, to be uncooperative?
Source: Schur, A

Jibo: short for jiggaboo, a racial insult
Source: SL

Jigger: back alley, passageway.  Jowlers were usually situated at the top and bottom ends of a section of housing. They usually led from one street into the next and allowed access to horse drawn bin wagons and coal wagons. The jowlers were linked by the jiggers which ran between the back to back houses.
Source: LS1

jigger-jerker :one who has or claims to have had frequent amorous adventures in back alleys.
Source: LS2

Jigger-rabbit. De jigger-rabbit. A stray cat. Some scousers also use this to refer to an alley rat.
Source: LS1, SL

Jiggered: tired, disaffected; this sometimes to refers to post-coital "letdown."
Source: Keyes ANS

Jimmy Riddle, to have a(rhyming): to urinate
Source: LS2
Source: LS3

Jink: a Jonah, a bringer of bad luck. (back-formation from jinx, assumed to be plural)
Source: LS2

jinking: rapid change of direction which is to throw the opposing players off the play
Source: GTH

Jinny Greenteeth: the ghost of a child-eating female said to haunt St. James Cemetery. In Lancashire tradition, Jinny Greenteeth was literally the green scum on ponds, but supposed to imply the presence of a water-sprite, or "boggart,"  a terror to children as they would pass a pond in which that appearance was seen. Old Lancashire saying to children: "Jenny Greenteeth'll fot thee if theaw'rt no' good."  Jenny resembled Grindelow, a water demon said to lurk at the bottom of a deep pit, and to stretch out its long arms to seize children who loiter near the banks, and drag them down below the surface, keeping them there until they are drowned.  A variant on that is Jenny lung arms, a water spirit supposed to clutch at little children and pull them into the stream or pit which it haunted.
Source: LS2, SL, GLD

jinxes: beer bottle tops
Source: SL

Job spike: vertical metal spike on which messages about jobs to be done were placed. In some businesses, it was known as a conker. Cf. "spike dancing" on this list.
Source: SL

jockey: a wedge of cheese used as a makeweight by the grocer to bring the cheese up to the requested weight, and sometimes a bit over that. Often the jockey would be given to children who were accompanying the buyer. It could also be a piece of bread added to get a loaf up to the legal weight, to the joy of the children who were sent to bring it home.
Source: Shaw, SL

Jockey: extra pay(dockers)
Source: LS1

Jockey: driver of a stolen car
Source: LS4

Jockey-bar. I'm livin jockey-bar. I am living in sin.
Source: LS1

Jockeys: french fried potatoes
Source: LS3

Jocks: testicles
Source: LS2
Source: LS3

Joe Bloggs: another generic form of reference or address, as for instance Joe Blow, etc.
Source: SI

Joe Gerk's: prison, usually the Walton gaol, (also known as "ther Gurk").  Cf. "gerk butty" on this list.
Source: LS2, LS3

Joe Baksi (rhyming): taxi
Source: LS3

Joe Palookad(rhyming): snookered, lured into a losing situation.
Source: LS3

Joe Soap: a generic name for John Q. Citizen, i.e., Joe Blow, etc

Joey: threepenny piece, or it could refer to the old silver sixpenny piece.
Source: LS1, LS3, Moloney

Joffer: rebellious child?
Source: SL

John Peel: one who boasts of his amatory successes
Source: LS2

Johnnies: foreign seamen; among some people, it seems to have become just another name for Pakestanis.
Source: Terry Cooke's Scotland Road; the Old Neighborhood
Source: SL

johnny, a: a contraceptive (male condom)
Source: SL

Join the mounties: to have sexual intercourse
Source: LS2

Jollop: medicine, expecially a liquid laxative.  Jollop powder was a popular purgative, too.  According to some memories, it was used to restart menstrual cycles, even sold as a magic powder to be sprinkled on the underwear of a desired mate.  Some credited it with the power to remove an evil spell from the house.
Source: LS2, SL

jones, to get a :  to feel the need for, to have an addiction to
Source:  SL, ODS

joss sticks: incense sticks burned to conceal the smell of cannabis
Source: SI

Jowler: back alley, passageway, a lane between back to back houses. Partridge cites Frank Shaw's opinion that it was a space where people passed cheek by jowl, but notes that one dialectal meaning of "jowl" is to bump into, which may explain the usage.  Other sources take "jowler" to mean a rather wider alley than a "jigger," which is also a "back entery."  Cf. "jigger" on this list.
Source: LS1, DS, PL

Jowler-yowler: an alley cat
Source: LS2

Joy-boy: a male prostitute
Source: LS2

Jud. George.
Source: LS1

Judas Burning: the custom in Liverpool's South End involving local children burning an effigy of Judas on Good Friday. Some Scousers think the custom was peculiar to Dingle. Many of the procedures there echo those of Guy Fawkes Day, but Judas Burning itself has Mediterranean roots, particularly in Portugal and Spain. No other English city is thought to show any trace of Judas Burning.
Source: CJB, MM

Judas Hole, the: the observation slit in a cell door
Source: SI

Judy. Me judy. My lady-friend.
Source: LS1

Judy-scuffer: woman police officer.
Source: LS1

jug: a pint
Source: LS2

Jug, ther: the Walton Jail
Source: LS2

Juge: to crowd in, or to nestle together
Source: LTB

Jump Sunday: the Sunday prior to the Grand National when the public tours and inspects the jumps; a reluctant lover or inadequate husband is said to save it for Jump Sunday
Source: LS2

jumped up:  This is said (often implying conceit or arrogance) of someone who has recently or suddenly risen in status or importance.  See "jump up."
Source: OED

jumpers(obsolete): bedbugs
Source: MEM

jumping figures: children's game
Source: DBAPOI

jump-up: a person envied for having made progress; one thought of as having gained undeserved promotion.
Source: LS2

Jungle juice: rum. It can also refer to bitters
Sources:LS1, LS3