Green’s Dictionary of Slang

Grecian v.

[? SE Grecian bend, ‘an affected carriage of the body, in which it is bent forward from the hips’ (OED)]

(W.I.) of a woman, to walk in a self-consciously ‘stylish’ manner, either arrogantly or proudly.

[WI]cited in Cassidy & LePage Dict. Jam. Eng. (1980).