A fork of Rural Dictionary
If someone says they're 'not about that life' it means that they don't or won't do something relating to that subject. It can be used in a variety of contexts and can be about a lot of things but it mostly used to reject someone inviting you to do something because you don't agree with it/don't like what they're doing/just don't want to.
It can also be edited to fit the purpose more by adding in a word before the word life to describe what kind of life said person is not about.
Example 1-
Person 1: Hey, I'm having a Sexy Party this weekend, wanna come?
Person 2: Nah, I'm not about that life. I'm sure you'll be coming enough for the both of us.
Example 2-
Person: Want to take a picture with me?
Person 2: Nope, I'm not about that selfie life.