Green’s Dictionary of Slang

slaughtering-knife n.

the penis.

1719

in D’Urfey Pills to Purge Melancholy VI 91: Sometimes I am a Butcher, / And then I feel fat Ware Sir; / And if the Flank he fleshed well, / I take no farther care Sir: / But in I thrust my Slaughtering-Knife, / Up to the Haft with speed Sir; / For all that ever I can do, / I cannot make it bleed Sir.