I don't want to drive my sister home
Why wouldn't you want to drive your sister home?
I'm too tired to drive her home.
Imagine if the roles were reversed! Would you want your sister to leave you stranded?  Family members should be available to help eachother out when they really need it.
I got my own life to worry about and I have no time to be bothered with useless crap.
You are right that you have your own life to live, but doesn't that also involve helping out family? Your family is an irreplaceable part of your life, and helping them when they need it is expected.