Short for dick, which is a slang for penis.
I got hit in the d with a baseball the other day.
D usually stands for dick. It is unknown when it was first used.
"I'm about to give my girl some big D."
POV: you looked this up because you’re going through the whole alphabet…
Daddy dick dominic he will glaze your donut and receives a dirty Kristina everyday
Wussup D what are you doing today I hope it’s me?!