Trash talking is a venerable tradition in epic fights. And in a game you can take advantage of the fact that talking is a free action to really lay down some heavy insults and innuendos.
But to avoid situations like this, we suggest you carefully script and rehearse your trash talking speeches before the game session.
Darth Vader: So, are we ready?
Luke: Let's roll.
GM: Annie, you and Jim are leaving tomorrow. This better not take all day.
Darth Vader: It won't.
Luke: If I chop my own head off now I'll be really annoyed at Yoda.
Darth Vader: So, Starkiller, we meet at last.
Luke: You're going down, old man.
Darth Vader: You must realise your puny Rebellion is over. You have nothing to live for. And once I kill you, my revenge will be complete.
Luke: Aha! What you don't realise is your revenge will only be complete when you kill yourself...
Luke: after you kill me...
Luke: assuming you do kill me...
Luke: which you won't because I'm totally killing you.
Darth Vader: Look, this fight was a lot more badass when you kept your face shut.