Green’s Dictionary of Slang

1. one who intercepts telegrams addressed to others.

1891

Cassell’s Sat. Journal Sept. 1036, col. 2: When a telegram sent to a specific person is surreptitiously made use of or drawn from by others, it is said to have been ‘milked;’ and those who thus steal are called milkers [F&H].

2. the vagina [it ‘milks’ the penis of semen].

1890–1904

Farmer & Henley Sl. and Its Analogues.

3. a masturbator.

1984

Partridge DSUE (8th edn) 738/1: C.19–20; ob.

4. an idler.

1894

A. Morrison Tales of Mean Streets 52: I’m a milker out an’ out, an’I ’ope I shall always remain a milker. The less a worker does the more ’as to be imployed, don’t they?

5. usu. in pl., the female breast.

1935		A.J. Pollock Und. Speaks.
2003		Buxom Milkers.com 🌐 The scantily clad enormous breast girl was flashing me her sexy buxom milkers crevice.
2005		Roger’s Profanisaurus in Viz Apr. 48: nipnosis n. Trance-like state induced by [...] a pair of bobbing milkers.
2012		‘Realoldbill‘ asstr.org 🌐 She was a fine looking youngster with a really impressive set of milkers, her shirt pasted to them by the rain.