Shucks are the husks of the corn ear. People sometimes say "aw,
shucks!" when they're slightly embarrassed. The implication is that
they use that word instead of saying some other word starting with
S that would not be as polite!
View page
A shuck is a husk or pod, like a corn husk or nut shell. Its'
vernacular, "aw shucks," is like saying garbage or junk. It isn't
an abbreviation, so it doesn't stand for anything.