In a Nutshell
Although schwenkel sounds like a Yiddish euphemism for a gentleman’s nether parts, in reality, it was just part of a medieval knight’s panoply. The schwenkel was a long banner at the top of a knight’s banner. Whether it constituted an honor or a disgrace is disputed.
The Whole Bushel
In the Middle Ages, knights were highly skilled warriors and war leaders serving the king. A “knight banneret” led troops into battle and was granted the privilege of carrying onto the field his own personal, square banner depicting his heraldic arms.
Sometimes, a longer tail or thin ribbon of fabric was fastened to the top of the banner—a schwenkel. The schwenkel could be a yard or longer. Red was a common color. The name may derive from the German schwenken, meaning “wave,” as in waving a flag.
Historians disagree on whether displaying the schwenkel was an honor given to a particularly talented knight, or a disgrace marking an incompetent or disfavored knight. The word may occasionally also refer to the whole banner with the long tail attached.