Green’s Dictionary of Slang

(UK juv.) the penis.

2001		OnLine Dict. of Playground Sl. 🌐 wankshaft n. vulg. The male penis.
2008		S. Packham Opposite Bastard 223: [T]hat frigid little todger-dodger [...] typical edge-of the bed virgin [...] Any bloody excuse to keep your wankshaft out of her furburger’.