faastie, adj. — Green’s Dictionary of Slang

faastie adj.

also fasty

[? Surinam Creole fiesti, nasty, or feisty adj. (1); but note SE fuss and thus faas v.]

1. (W.I., Jam.) rude, impertinent, impudent.

1980		(con. 1950s) M. Thelwell Harder They Come 50: But she did also faastie so that none of the man dem she see satisfy her.
1981		N. Farki Countryman Karl Black 29: The conductress was still quarrelling. ‘Damn fasty shit-house!’.
1991		L.E. Adams Jam. Patois 42: No bada fas’ wid mi! – Don’t meddle with me.

2. (UK black) unpleasant, distasteful.

2000

personal correspondence 10 July: Some more stuff for your files. . . I heard ‘faystie’ used by kids in Stockwell in the sense of horrible.