Green’s Dictionary of Slang

crow n.3

[? one crows or exults over it]

an unexpected or fluky piece of luck; usu. in phr. regular crow.

[UK]Hotten Sl. Dict.
[UK]Sl. Dict.
[UK]T.B. Reed Cock House Fellsgarth 139: ‘[W]ouldn't it be rather a crow for them to see that we are licked without them?’.