When one isn't able to get an erection.
Whereas the stalk won't hold up the head.
Usually from a temporary reason ie. Nerves, drunk etc.
A term used jokingly on construction crews.
The man didn't have sex, due to a case of cabbage fever.
The uncontrollable urge to shave one's eyebrows
"What happened to Tom"
"He got cabbage patch fever during quarentine"