Vader: Obi-Wan never told you what happened to your farter.
Luke: He told me enough! He told me YOU tooted him.
Vader: No... I am your farter.
Luke: NOOOOOOOOOOOOOOOOOOO!!!
And now, vanquished by his only son, Vader turns slowly and mumbles to himself, "...Man, I've just gotta get more ventilation
in this helmet..."