Green’s Dictionary of Slang

dressed adj.

[SE dressed up]

(US black) of a car, filled with every conceivable decoration, gimmick and similar flashy adornment.

[UK](con. 1916) J.M. Saunders Wings (1928) 34: His father knew the ‘high powered’ car for a dressed-up flivver.
[US]R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].

SE in slang uses

In phrases

dressed down (adj.) (also dressed tight) [but note recent ‘dress-down Friday’, a day on which office workers are allowed to dress casually]

(US black) very well dressed.

[US]Eble Campus Sl. Mar. 2: dressed down – dressed up (black dialect originally).
[US]E. Folb Runnin’ Down Some Lines 111: There is even a larger vocabulary that refers to being well dressed ([...] dressed tight, dressed down, dapped down, choked down).
[US]‘Master Pimp’ Pimp’s Rap 3: They were dressed down in leather and were talking slick out the side of their necks.
dressed in (adj.) [i.e. dressed in newly issued clothes]

(US prison) clothed in a fresh uniform that denotes the new inmate; by ext. the new inmate themselves.

[US]Monteleone Criminal Sl. (rev. edn) 75: dressed in numbers To put on prison uniform upon entering prison.
[US]Bentley & Corbett Prison Sl. 26: Dressed In When a person first arrives in prison he is issued prison clothing. This clothing is new, usually oversized and easily recognizable by the other inmates. The conspicuous new inmate is referred to as dressed in.
dressed to death (adj.)

(US) dressed up fashionably / smartly.

[US]Eve. Star (Wash., DC) 24 Dec. 1/5: Wal, sir, he was drest to death in the handsummest kind of store-clothes.
dressed up like a lighthouse (adj.)

(US) flashily, ostentatiously dressed.

[US]J.T. Farrell Gas-House McGinty 166: He’s all dressed up like a lighthouse.
[US](con. 1920s) J.T. Farrell Young Manhood in Studs Lonigan (1936) 328: I saw him at Church last Sunday, feeling so swell, and dressed up like a lighthouse.
dressed up like a sore finger/thumb (adj.) (also dolled up like a sore finger/thumb)

(Aus./N.Z./US) overdressed, flashily dressed.

[US]El Paso Herald 1 Mar. 23/7: The 1913 classs is considering a plan to have all the girl graduates dress in simple [...] gowns [...] instead of being dressed up like a sore thumb.
[US]Day Book (Chicago) 13 Nov. 32/2: The muscial inclinations of the general public are all dressed like a sore finger nowadays. All rags.
[US]Sun (NY) 6 Jan. 55/6: Why’re you all dresssed up like a sore finger? [...] You’re not figuring on crashing the gate at the movies in that soup and fish scenery, are you?
[Aus]W.H. Downing Digger Dialects 46: sore finger — An over-dressed person (e.g., ‘dolled’ up like a sore finger).
[Aus](con. WWI) A.G. Pretty Gloss. of Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: sore finger. An overdressed person. (eg. ‘dolled’ up like a sore finger.).
[Aus]Cusack & James Come in Spinner (1960) 136: It’d be safe enough with the door open and her dressed up like a sore thumb; even an old wolf like Alfalfa would hesitate before he ruined a frock like this.
[Aus]N. Keesing Lily on the Dustbin 87: Young people who [...] ‘dress up like a sore thumb’ or ‘the cat’s meow’ are fair game for domestic wits.
[Aus]G. Seal Lingo 198: Other uses of up include [...] dressed up like a sore thumb in sartorial splendour.