Green’s Dictionary of Slang

the vagina; thus the fake-threatening phr. I’ll have your whelk.

1890–1904		Farmer & Henley Sl. and Its Analogues.
1956		J. Curtis Look Long Upon a Monkey 159: ‘Our days of philandering are over. Disappointed?’ [...] ‘You might let a girl have her hand back then, damn you! If you don’t want the whelks, don’t muck ’em about.’.