You know how it goes. You're at a holiday party and almost immediately, you're confronted by someone you have literally zero interest conversing with, but such is life.
So you can discuss...
Your parents' friends
Beat them to the things you know they are going to say by giving a response before they ask.
For example:
"Look how tall and old I have gotten! Haven't I grown into a beautiful young woman?"
"Aren't you wondering what my major is and what I am going to do with it?"
"Yes, I love college, my roommates, and the food on campus!"
People you are not sure how you know nor why they are there
This is the ultimate game. You can never admit that you do not know them because I am sure they are about to tell you how cute you were as a baby. So, think about the vaguest question you can ask.... "How's the family?" or ever better, "How are things?"
People you are sure are confusing you for some else (usually a sibling, cousin or friend)
In this case, you have a few options. You could correct their honest mistake which would undoubtedly lead to a few seconds of awkward silence while they attempt to figure out something interesting about you. Or you could choose the more interesting option, a fake update on the person you are mistaken for.
For example:
"My husband is great! He has decided to take up Elvis impersonating and our open marriage is really working. My one-year-old is even better. He has decided to drop out of daycare to find himself and I am now a sculptor."
or
"Things are great! I have decided to sell all of my belongings and live on my boat while sailing around the world! I haven't told my family yet, though so it's just between you and me!"
And finally to anyone who asks why you're single
Make things as uncomfortable as possible by responding with "Why? You single?" or maybe "Are you asking me out?"
Happy mingling.