When Macduff's son defends his father's honor when the murderers sent by Macbeth call Macduff a traitor in Macbeth, they wind up stabbing the son:
Enter Murderers.
FIRST MURDERER: Where is your husband?
LADY MACDUFF: I hope, in no place so unsanctified where such as thou mayst find him.
FIRST MURDERER: He’s a traitor.
SON: Thou liest, thou shag-ear’d villain!
FIRST MURDERER: What, you egg! [Stabbing him.] Young fry of treachery!
-Macbeth
What's up with the "What, you egg!" line? Why does the murderer call the son an egg? It seems completely unrelated to anything else, and doesn't seem like a witty comeback to the son's "shag-ear'd villain" insult.