Implicating knot -> erection.

Reason: A knot is only formed when the penis is erect. If this isn't added, then please add knot --> penis

That would make sense, if art was always biologically/anatomically accurate.
Sadly, there are plenty of flaccid penises out there with knots.

We're talking about a genre where you see a human penis on just about every species and where just about every species has been drawn with a "knot". Artists, as Hammie suggested, don't respect biology. Heck, there's even a well-known pair of statues of lions in the city in which I live which were sculpted with canine-like sheathes, and we all know (or should know) that felines do not have those.

Bottom line: This implication should not be implemented because it will introduce more problems than it solves.