Performed by four people with hands joined: To Duck for the Oyster, the active lady ducks partially through an arch made by the inactive couple and backs out. To Dig for the Clam, the active man does the same thing. In other areas, Duck for the Oyster meant that the active couple ducked partially thru the arch made by the inactives and backed out. Then on Dig for the Clam, the inactive couple partially ducked thru the arch made by the actives and backed out.
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.