NOTE: While "the old man" refers to your father, "the old lady" refers to your wife or girlfriend, not your mother. Calling your mother "the old lady" is considered disrespectful.
Luke: "I know you're old. Please stop distracting me while I'm trying to kill you."
Darth Vader: "I didn't say I am AN old man, I said I'm THE old man. As in yours."
Luke: "Oh shit dude, for reals? You're my dad? That's a bummer, considering that you're like the most evil person ever and I've dedicated my life to trying to kill you."
Darth Vader: "I know this must be a tough time for you son. There's a family reunion next week though, and I'd be delighted if you would come with me and meet your Uncle Jimmy and Aunt Susan."
Luke: "Gee...um...dad. I don't know, I'll have to think about it."
Darth Vader: "Ok, I understand. In the meantime, quit trying to bone Princess Leia. She's your sister."
Luke: "DAMN! Glad I used a rubber!"
Its usually a term of respect, but many times just used as to refer to the commander without any judgement of respect or disrespect. NOTE = this term is never used in the presence of the old man / commander.
Soldier 2: Sarge said go straighten your shit up, looks like the old man stopped in unexpectedly.