I don't give two and a half shits
You really, REALLY don't care about what someone just told you.
Brody: Hey, I just found this really funny video I wanna show you, it's about this-
Ryan: I don't GIVE two and a half shits, alright?!
Ryan: I don't GIVE two and a half shits, alright?!
I don't give two and a half shits
Combining a reference to two and a half men and the fact that you care so little about what the other person's saying.
-Hey, guess what I was doing last night?
-You know what? I don't give two and a half shits!
-You know what? I don't give two and a half shits!