When a woman allows a man to have anal intercourse with her while she's constipated, so that the penis helps loosen the stoole. The result is a penis covered in feces.

Originally phrased, "shit-dick," but through the course of language development and regional dialects, the pronunciation changed to the current, "shiduck."
Annie: He looks so fine.
Marylou: I would go down on him so quickly!

Annie : I heard he's a dentist, too.
Marylou: In that case I'll also shiduck him until he loves me.
by Hugod February 19, 2018
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