A mysterious ad appeared over the weekend in The Washington Post Classifieds, under the Electronics category, sandwiched between Collectibles and Furniture. It took up three lines and it read: “WANTED — Flux Capacitor — Needed to complete an important project. Must be in good condition. 571-444-5995.”

Because, after all, what use is a busted flux capacitor? You’d never get your DeLorean to achieve time travel, as explained in “Back to the Future,” that documentary movie released in 1985.

I called the number and got a recording. It was of a harried-sounding man saying, “If my calculations are correct, when this baby hits 88 miles per hour, we’re gonna see some serious [stuff].”

I left a message and my cellphone number.

An hour later my phone chimed, signaling a text: “Do you have the item?”

I texted back: “Do you have the money?”

I was bluffing, but he didn’t need to know that. After all, he could have been Libyan.

As it turns out, he isn’t. He’s a 35-year-old tech entrepreneur who lives in Loudoun County, Va. He doesn’t want me to use his name because he does work with the government and thinks some clients might be freaked out that he occasionally puts silly ads in major newspapers. Let’s call him “Doc.”

“I’m just a big nerd,” Doc said.

He first ran the ad in The Post over April Fools’ Day in 2017. (It’s also appeared in the Express.)

He didn’t get many responses that time, maybe because he used a California area code. (He has a service that allows him to use different phone numbers.) This time around, about a dozen people have called. After playing that bit of movie dialogue, the calls go directly to voice mail.

“Some people call and they’re just laughing,” Doc said. “Some people are like, ‘Hey, this is cool.’ ”

One person calling from what Doc said is a government agency left this message: “I just wanted to thank you. I posted it to my Facebook page, so I hope you actually will get a call so that somebody who has a flux capacitor in good condition can provide it to you so you can complete your important project.”

Doc is from the Midwest. His family life wasn’t that great, he said. No trauma or abuse, but when it came to raising kids, his parents were sort of clueless. He doesn’t have fond memories of growing up.

But things were different in the 1980s movies Doc came to watch over and over. He loved how in a 1980s movie, the problems that families have are resolved in 90 minutes.

Doc has his own company now. He has a TV in his office that plays a constant rotation of “Ghostbusters,” “Raiders of the Lost Ark,” “Back to the Future” and other classics of their ilk.

He collects replicas of movie props, including the hoverboard that Marty McFly rode and the self-lacing Nikes he wore. Doc even owns a DeLorean. (“I’m in one right now, waiting to go to lunch,” he said.)

Doc’s stunt — placing “Back to the Future”-inspired ads — reminded me of the 2014 movie “Safety Not Guaranteed,” based on a joke ad a writer placed inviting people to travel back in time with him.

“Yeah, it was okay,” he said of that film.

I asked Doc whether he put his flux capacitor ad on Craigslist too.

“No,” he said. “Craigslist is not for normal people.”

As for time travel itself, Doc doesn’t believe in it.

“I’m not crazy,” he said. “It’s definitely not a thing. The way I look at it, we do have the ability to travel in time, but only in one direction: the future, one day at a time. My catch phrase is, the future is right now.”

(Thanks to reader Mitch Gerber for pointing the ad out to me.)

Chinese whispers

Did you see that story about how some people are worried Chinese-made Metro cars could spy on riders? The cameras could beam images to Beijing, microphones could capture the casual conversations of government officials on their commutes.

I say, bring it on. Let the Chinese listen.

Their operatives will hear the train operators’ redundant announcements: “This is the last and final station in the District of Columbia.” (Last and final? Pick one, please.)

They will hear both “We are holding at this station. There is a train directly in front of us” and “Please do not crowd this train. There is a train directly behind us.”

Isn’t that what a subway is, a regular progression of trains?

They will hear inane phone conversations (“I just left Takoma”) and the tinny sounds of clueless riders listening to their crappy music without earphones.

Just as the Soviet Union was brought down by its attempts to keep up with Ronald Reagan’s Star Wars program, so the annoyance and drudgery of transcribing hours and hours of Metro banality will bring the Chinese Communist Party to its knees.

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/john-kelly.