Green’s Dictionary of Slang

dirk n.1

[proper name]

the penis.

[UK] ‘As I Cam O’er the Cairney Mount’ in Burns Merry Muses of Caledonia (1965) 140: The Highland laddie drew his durk and / sheath’d in my wanton leather.
[UK] ‘A Celebrated Flash Parody’ in Regular Thing, And No Mistake 56: The Highland lad he drew his dirk and / sheathed into my wanton leather.
[UK]Farmer & Henley Sl. and Its Analogues.
[US] in G. Legman Limerick (1953) 191: She danced with a Turk / Till he got in his dirk, / And now she can’t button her pants.
[US]Poston ‘Problems in the Study of Campus Sl.’ in AS XXXIX:2 118: Two variants which are probably Midwestern, dirk and dork, also meaning ‘penis’.