if someone is annoying you, just say "they're not even worth my time."
if someone is making you upset, just say "look how carless and mean he/she/they are/is."
if someone doesn't believe you, just say "i can't do anything to change your mind."
if someone doesn't like the way you are, or they want to change something about you, say "i didn't make myself like this. this is how i was born. take me as i am, or don't accept me at all."