half-rocked, adj. — Green’s Dictionary of Slang

half-rocked adj.

[? one who has not been fully rocked in the cradle and is thus still infantile]

incompetent, inadequate, foolish.

1860		Hotten Dict. of Modern Sl. etc. (2nd edn).
1873		Sl. Dict.
1914		C. Holme Lonely Plough (1931) 14: But Lup just sat there like a half-rocked ’un.