Shemo is Italian for idiot, embarrassment, crazy person. So to be a half a shem the worst form of shemo, your not even adequate enough to be considered a fully functioning shemo....your just half a shem.
"My friends left me at the concert stuck with no ride and I was standing there like half a shem"
2) Guiseppe Carlino
"My friends left me at the concert stuck with no ride and I was standing there like half a shem"