An inside look at the infamous banned list at the Chinatown cocktail bar.

Updated 1:50 p.m.

Hop Sing Laundromat’s banned list is almost as famous as the Chinatown bar itself.

In the six years since proprietor Lê began welcoming booze aficionados to his dusky cocktail house behind an ornate Race Street gate, the list of folks who’ll never be allowed back in has swelled to nearly 3,000. People get vetoed for any number of reasons — see below for the most popular ones — but Lê didn’t start out with the intent to embargo such a large number.

“At the beginning, [the list] was just a handwritten note tacked up in the back,” he said. “Then we realized how many assholes there are.”

Nowadays, the list is maintained as a computer spreadsheet — something anyone who follows Lê on social media would know, since he revels in shame-posting anonymized screenshots.

Here’s how the banned list system works. When you reach the front of the line (only 50 people are allowed in at once) and get to the front door, you’re asked to surrender your identification and wait in the penny-tiled anteroom.

The ID is then scanned by specialized hardware that’s linked to the spreadsheet. An algorithm checks the info against the current database. All of this happens in under two seconds — two demo tries were recorded at 1.7 seconds and 1.6 seconds, respectively.

If it matches a previous entry that’s tagged “BANNED,” you’re out of luck. If not, you’re in.

Some prospective customers never end up entering the bar. “People will jump up on the lobby bench and almost knock it over,” Lê said. “What are they thinking?”

At least 89 people have been prohibited because of lobby shenanigans of that sort. That’s only one more than the 88 folks who’ve been banned for talking trash or acting dumb even before they got past the gate.

These numbers are calculable because of the notations staff adds to an entry after deciding to mark someone. Each ban must be vetted by Lê himself to become final, but “very rarely do I overrule them.” The level of detail in the list notes has grown over the past couple years.

This chart shows what’s most likely to get someone forbidden from what Lê likes to call “the world’s best North Korean cocktail bar”:

No. 1: Bad tips

Cheapskates take heed: the top reason people land on Hop Sing’s banned list, by far, is leaving a bad tip. A full 626 entries — around 22 percent of the total — mention some kind of gratuity aggrievement. Notes document everything from groups giving $2 on hundred-dollar checks to couples leaving 30 cents because “they forgot to get cash.”

“We told you cash only in the lobby,” said Lê, veins pulsing slightly with frustration, “but you decide to ignore us?”

No. 2: Bad review

Influencer culture has no home in Lê’s world. Staff regularly scours online reviews, and if it’s discovered someone has gone on Yelp (or Google or Facebook) to post unfavorable comments after a Hop Sing visit — like at least 411 people have — they won’t get back in.

If you’re not the review-writing kind but your compatriot is, watch out. A bad post by one person can get everyone in their party banned.

No. 3: Taking a photo

From the very first day of business back in 2012, photos have been strictly forbidden inside the Laundromat’s den. Upwards of 318 people seem to have taken that as a challenge, including 34 brave (or foolish) souls who actually tagged the bar when posting pics to Instagram.

No. 4: Walking out

Mystery around bar’s reputation is strong enough that it draws destination seekers who just want a peek inside. At least 316 people have gone through the effort of waiting in line, surrendering their ID for a check — then promptly walked out without ordering a drink.

“On a busy night, we have to scramble to set up a table [for new customers] and after all that, they just want a ‘tour’?” said Lê. If people banned for this reason return, he’ll tell them something like, “Sorry, the zoo is closed today.”

Other egregious occurrences that occur on a repeated basis:

Guzzling water straight out the large bottle left on tables to refill glasses

“Humping” a chair or otherwise treating the bar’s vintage seats without respect

Pulling the petals out of the flowers that grace each table

On occasion, Lê will let people off with a warning — there are 300 warning notations in the database — because once you’re on the banned list, you’re pretty much on it for life.

There has been one single instance of someone getting restitution, and that’s only because the person was incredibly penitent. After being banned because a friend posted a pic to Instagram, the woman waited in line almost every Saturday, and when turned away, just silently left without making a fuss. After weeks of this, Lê had his staff tell her if she wanted to return, she should write him a handwritten letter.

“I didn’t think she’d do it!” Lê exclaimed wondrously. “But she did.”