Every reality show has its own set of truths — those things that happen every single season, no matter who’s in the cast.

The one "Top Model" constant is that the judges will contradict themselves so much that it will make your head spin.

One minute, they’ll be your best buddy, telling you they love you like they’re your Momma, the next they’re punishing you for weeks because you made the simple, comedic note that a stick one of them was holding might have required a proctologist for removal (I still love ya, CariDee).

Case in point: All Tyra and company do is prattle on about how the girls must do everything they’re instructed to, even if it means driving right up to death’s door.

Yet this week, when CariDee started shaking with hypothermia while posing in the pool with Amanda, she was reprimanded for not explaining how cold she was sooner, and then later shamed for not being able to handle her temperatures better.

How’s a 90-pound girl with hypothermia supposed to know which way’s up with so many contradictions abounding?

Meanwhile, hats off to “The Real World” gang for getting into their main commandment — thou shalt make an utter fool of thouself after ingesting near-lethal amounts of alcohol — so quickly in the season.

Resident stud Alex managed to not only hook up with two of his three female roommates within his first 36 hours in the house, but also did an almost believable job of acting absolutely shocked when girl No. 1 was none-too-pleased.

The two girls declared themselves best friends repeatedly, cried and hugged and collectively decided he was a jerk, only to play right into his hand later that night.

I’ve got to give it up for “The Real World” — the show that makes my twenties, no matter how out of control they were, seem comparatively sane and sober.

And then there’s “Survivor” and its one ceaseless ritual: that Jeff Probst will narrate those immunity challenges in a slightly patronizing, very game-show-host tone that’s irritating when you’re listening to it from the comfort of your couch.

I can only imagine how infuriating it is when you’re, say, starving and trying to add numbers together and untie knots in a desperate attempt not to get kicked off the show that night and he’s screaming, “Jonathan was wrong, has to start again — was Ozzy right? It’s been a long 30 days,” as he paces with the kind of smugness that only comes from knowing you’re sleeping in a bed and eating what you want for dinner while these dirty fools scramble over less than a seventh of your salary.

While Probst may drive Survivors, not to mention viewers, crazy with his self-satisfied speeches that account every last detail of each challenge, having an annoying host is surely Reality Show Commandment No. 1.

Anna David has been on staff at Premiere and Parenting magazines and wrote a sex and relationship column for Razor. She’s done celebrity cover stories, first-person essays and reported pieces for The L.A. Times, Vanity Fair, Cosmo, People, Us Weekly, Redbook, Self, Details, Stuff, TV Guide, Women’s Health, Ocean Drive, Vegas, The Saturday Telegraph, Esquire UK, Teen Vogue, Variety, The New York Post, LA Confidential, Distinction, Calabasas, Tatler (Hong Kong), King, Fade In, Emmy and Maxim, among others.