Pop quiz, hotshot: There's a bunch of rat turds in your kitchen. Once a city inspector sees them, your health score drops. If it drops to SF's bottom 5 percent, Yelp places a nasty note on your page. What do you do?

Well, if you're some San Francisco restaurants, you apparently write a check — a payment to retake that pop quiz, if you will. It's part of a pilot program, NBC Bay Area reports, that "allows poorly-rated restaurants to purchase an 'inspection do-over' in hopes of earning a better health score."

It's an effort by San Francisco's Department of Public Health's Environmental Health Retail Food Safety Program, the folks charged with performing as many as three annual random, unannounced inspections of the city's "restaurants, markets, and all other retail food operations." The score you get during that inspection is the one you keep until your next inspection, and it must be posted in a "clearly visible place to the general public and patrons of the establishment," the DPH says.

However, under a new and "little-known pilot program," NBC reports, "Low-scoring restaurants can pay $191 to receive a new inspection within 30 days, which can provide the business with a brand-new score."

Lisa O’Malley, one of three supervisors in charge of San Francisco’s restaurant inspection program, tells NBC that so far only four restaurants have paid to retake the test. Westfield Centre's M.Y. China recently turned their 63 (anything under 70 is considered "poor" by the DPH) to a 93 (scores over 90 are considered "good") on the retake, after their initial inspection (you can see their inspection history here) yielded nine violations, three of which were considered "high risk" by the agency.

Mason and Market's Farmerbrown also participated in the program, raising their score from 79 to 90 after an inspection revealed (among other things) a "High risk vermin infestation" (here's their inspection history), which NBC says was noted because "inspectors found 'rodent droppings' throughout the restaurant."

O'Malley disputes that this is a case of paying to retake a test, as “It is not as simple as they will pay a fee to try to get a higher score. This is about changing bad behavior patterns within a food facility,” she tells NBC. Even on the return inspection, "we do not tell them when we are coming... We did not call and say ‘we will be there at 2 o’clock on Friday.’ We don’t do that. So it is a surprise inspection.”

Vincent Sollitto, senior vice president at Yelp, which as previously reported makes an effort to warn users away from poor-scoring restaurants by way of an alarming note on their Yelp page, scoffs at O'Malley's characterization of the program.

“If businesses can whitewash their reputations by paying for new scores then the whole process breaks down,” he tells NBC.

“Businesses are trying to avoid the ramifications of a bad score on a pop inspection by paying for a new one...When [a restaurant] didn't think anyone was paying attention, they weren't following the proper hygiene, and that's what consumers really want to know. Wouldn’t you want to know what happens when no one's looking?"

“We think the city should be siding with consumers and not allowing businesses a do-over,” Sollitto said. “When I was in school, if I failed a pop quiz I didn’t get a second-chance the next day. That was my grade.”

According to NBC, Yelp will now keep poor health score alerts active for six months, "even if a restaurant pays to get a new score" and as of Wednesday will revise their bad score alert on all the city's scofflaw restaurant pages (about 60, Sollitto says) with a note containing pointed lines like "Some restaurants have lobbied San Francisco to accept payments in exchange for new scored based on prearranged inspections" and a call to users to complain to the DPH regarding this program.

The DPH is unmoved by Yelp's words of scorn, however, and O’Malley says they they expect "10 to 20 more restaurants" to pay to for re-inspection in the coming months After that, the city will "review the results before fully implementing its pilot program."

“Here in San Francisco, we build bridges with people; we want to protect public health,” O’Malley told NBC.

“We are doing our job, and we are doing that through enforcement, and we are doing that through education.”

Speaking of education, the DPH does allow you to educate yourself: You can look up the health score history of any SF restaurant here. Check your favorite dive, if you dare!

Related: Yelp Now Explicitly Warning You Off Restaurants With Poor Health Scores