"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.
In Macross Plus, Isamu snaps at Myung's self-pity by telling her that sometimes life isn't fair and that she needs to deal with it, instead of feeling sorry for herself.
In the second season of Yu-Gi-Oh! GX (the dub only) Sartorious' henchman X tells Jaden this, telling him that you can't always get everything you want, emphasizing it by saying that when he was Jaden's age, he used to dream of being a pastry chef. (Of course, this sort of comes off as a Broken Aesop considering the type of person X is, and considering that he seems to love his actual job a little too much, that of an Amoral Attorney who is willing to use cruel and underhanded methods to crush the will of his opponent.)
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.
In the Batman: The Animated Series episode "What is Reality?", the Riddler's final challenge to Batman before his virtual world shuts down is: "If the planet were equitable, I'd still have my old job." This actually has a double meaning; since he previously had told Batman that his criminal career was a personal matter (in the previous episode he appeared in), he's saying if life were fair, his old employer would never have cheated and fired him. But it's also a riddle that tells the hero where he is: The sentence can be rephrased to say, "If the world was fair, I'd still have my ex-position", meaning he's at the World's Fair Exposition.