"Life isn't fair. Deal with it." Fiction Isn't Fair and neither is Real Life. Another one of those Stock Phrases, usually particularly irritating to the character it's being told to. Another way of saying "deal with it". Sometimes used to respond to an accusation that the character wasn't fighting fair.
Hey, thumbdick, I was a damn good shrink. Nineteen years I worked with a lot of people through a lot of shit. OK, I slept with a patient or two. It's not like I didn't care about them. I loved being a doctor. I used to not charge half my patients. Then the fucking state comes along, they send in some bitch undercover, and I'm fucked. Life isn't fair, is it?
"You and Black, you're two of a kind: sentimental children, forever whining about how bitterly unfair your lives have been. Well, it may have escaped your notice, but life isn't fair. Your blessed father knew that; in fact, he frequently saw to it!"
"Life is pain. Anyone who says differently is selling something."
"Life isn't fair. It's just fairer than death, that's all."
In Soul Music, Crusty Caretaker Albert explains that Susan is the only eligible replacement for Death, and being a typical teenager at heart Susan eventually resorts to complaining "It's not fair!" Albert retorts, dripping with sarcasm, that she can go explain that to the universe at large and see how far it gets her.
This is also seen earlier in Mort when protesting the unfairness of someone's death.
There is no fair. There is no justice. There is just me.
Life isn't fair, Will. I mean, was it fair when Bambi's mother died?
In one episode of Babylon 5, Marcus the Ranger expresses a rather enlightened outlook on the subject:
You know, I used to think that it was awful that life was so unfair. Then I thought, wouldn't it be much worse if life were fair, and all the terrible things that happen to us come because we actually deserve them? So, now I take great comfort in the general hostility and unfairness of the universe.