"The Yelper Special" is a song featured in the Season Nineteen episode, "You're Not Yelping".
Background
When restaurant owners started to realize that the opinions of Yelp-reviewers were meaningless because everyone of them thought they were the leader, they decided to stop serving Yelp-reviewers with respect. Every time a Yelp-reviewer came into their restaurant, they'd do something horrible to their food without them even noticing.
The two most popular things would be smearing their boogers on it and ejaculating on it. At the end of "You're Not Yelping", a montage of all of the food defacing played with this song featured.
Lyrics
So you're one of the yelpers special blessed,
You demand a restaurants' very best.
Well they're gonna treat you special,
I'm telling you chum.
Now get yourself ready for some boogers and cum.
Boogers and cum, that's called the Yelper special.
Boogers and cum, say what's that on your pretzel?
Your online critiques are real useful to some,
Now have a good time eating boogers and cum.
Boogers and cum, someone farted on your salad?
Boogers and cum, but your decor critiques are valid.
You think you're special like you're A-number one,
Well, there's a whole lot of special in boogers and cum.
Boogers and cum, how 'bout some feces with your flounder?
Boogers and cum, you like that queefy quarter pounder?
[yelper] What's that spice that feels tangy on my tongue?
[waiter] Oh, that's the yuzu pepper, (walks away and mutters to himself) along with some boogers and cum.
[Davíd] Here you are, sir.
[Cartman] Thank you, David, that's good service.
[Davíd] I will bring you food every day, my friend.
[Cartman] Mmm, is that a Jalapeño cream sauce?
[Davíd] Yes, my father made it just for you.
[Cartman] Hmm, it's tart, but savory.
Boogers and cum, being a food critic's easy.
Boogers and cum, oh, you feel a little queasy?
Do you need a diagnosis? Well, the doctor's got one.
[doctor] Your stomach seems to be filled with boogers and cum.
Boogers and cum, piss in your potatoes.
Boogers and cum, some guys' shit on your tomatoes.
Alright, fancy food critics, looks like you've won,
Now please enjoy all the booo-hooo-geeers... booo-hooo-geeers... annnd cuuummm!