Green’s Dictionary of Slang

blot n.1

1. the vagina [pun on play backgammon under backgammon n.].

H. Neville Newes from the New Exchange 11: My Lord […] may play well, yet the Col. hit the Blot oftner in his Ladie’s Tables .

2. an unpleasant person [a fig. ‘blot on the landscape’].

[Aus]W.A. Sun. Times (Perth) 14 Apr. 1/1: These bibulous crimson blots did not appear before the beak. Why?
[UK]J. Masefield Everlasting Mercy 33: Maligning, peering, hinting, lying, / Male and female human blots / Who would, but daren’t be, whores and sots.
[UK]P. Marks Plastic Age 259: ‘I’m a blot,’ he declared mournfully.
[UK]‘Leslie Charteris’ Enter the Saint 84: You filthy blots! [...] You warts — you flaming, verminous —.
[UK]N. Marsh Death in Ecstasy 126: Must we undress this unpleasant old blot?
[UK]Wodehouse Mating Season 71: I can rely on you to foil and baffle that foul blot.
[UK]Wodehouse Much Obliged, Jeeves 9: Hullo to you, you young blot. Are you sober?

3. (Aus.) the anus, the buttocks.

[Aus]Baker Aus. Lang.
[Aus]J. O’Grady Gone Troppo (1969) 184: If I ever go back to that louse-bound shack / I’ll give that boss some wingein’; / I’ll shove the lot in his old brown blot, / Startin’ with his bloody engine.
[Aus](con. 1940s–60s) ‘The Shearer’s Lament’ in Hogbotel & ffuckes Snatches and Lays 73: You can jam the lot up your dirty black blot.
[Aus]D. Ireland Burn 40: I’ve sat on my blot for the last twenty-five years, here.
[Aus]G. Seal Lingo 88: The extent and variety of the Lingo terms for genitals and other body areas hints at a determined, if perverse, use of euphemism to avoid the use of perfectly respectable words like testicles, penis, vagina, and posterior. Such terms, though, seem sterile and colourless to the Lingoist who prefers such delights as [...] date, fanny, arse, bum dot, backside (spot your dot being an affectionate invitation to take a seat), blot, to name only a very, very few.

4. (US Und.) the underworld.

[US]Goldin et al. DAUL 30/1: Blot, the. (Pronounced blat) The underworld.
[US]C. Hamilton Men of the Und. 287: A copper-hearted flunky who lacks the moxie to stick with the blot.