President Trump's confession that he used to ride between the subway cars as a kid in Queens prompted the NYPD transit chief to issue a curt, if obvious, reminder: "Please don't ride between the subway cars."

NYPD Transit Chief Joseph Fox tweeted that in response to the New York Times article revealing Trump's admission of hanging out between cars on moving trains. It is illegal to do so.

"I know the subway system very well," he told The New York Times Wednesday, after admitting it has been "a long time" since he took the subway. "I used to take it to Kew-Forest School, in Forest Hills, when I lived in Queens. And I'd take the subway to school. Seems a long time ago. I'd take it from Jamaica, 179th Street. Jamaica, right? To Forest Hills. I understand the subway very well. I used to ride between the cars."

He said his parents "weren't thrilled when they heard that."

Please don't ride between the subway cars. https://t.co/AVC4V1Nq2e — NYPD Transit (@NYPDTransit) April 6, 2017

Trump was reflecting on his experience with transit in New York City as he mulls how to introduce his $1 trillion infrastructure bill in Washington.

Trump also veered to talk about the battered metal median guards on the Van Wyck Expressway near his childhood home in Queens: "It's the worst garbage. And I also think it's dangerous because it's a spear. And if you hit those things, they come flying apart. And if you're driving, you've got yourself a problem."

Trump told the Times hadn't personally driven in a while.

And he called the city's airports "a horror show," adding "I've traveled the world, I know the world."

[NATL-NY]See Inside Trump's Childhood Home in Queens

But the president isn't saying whether he plans to include to major New York City transportation projects that his budget for next year would defund, according to the Times. He may wield the infrastructure bill as a negotiation tactic to again try to repeal the Affordable Care Act or a tax code overhaul.

"Infrastructure is so popular that I might want to use it for another bill," said Trump. "Infrastructure is so popular with the Democrats and pretty popular with the Republicans. A lot of Republicans want infrastructure, too."

The Second Avenue subway expansion and a new train tunnel under the Hudson River were supposed to be getting federal funding under the Obama administration. The necessity for the tunnel -- part of the long-discussed Gateway Project -- has been spotlighted amid the ongoing commuter nightmare stemming from the New Jersey Transit train derailment at Penn Station Monday.