TLIK, I originally heard it as a Yekke and Chossid at shalishudis joke, and I think it was a piece of herring.
The other Yekke/Chossid/shalishudis/herring joke is that the Yekke tells the gabbai to prepare an extra piece of herring for shalishudis because his chassidishe cousin is coming for Shabbos.
One fellow doesn’t show up, though, and everyone is eying the piece of herring but no one takes it.
Suddenly, the lights go out, and a loud shriek is heard.
The lights go back on, and a hand with ten forks in it is seen.