The bucks stop here!

After being spotted boarding Air Force One with a bunch of crisp Andrew Jacksons spilling out of his pocket, President Trump explained that he generally keeps a wad of $20 bills with him — so he can leave a nice tip.

“I do like leaving tips to the hotel. I like to carry a little something. I like to give tips to the hotel,” Trump told reporters upon returning to Washington DC from California on Wednesday.

“I’m telling you, maybe a president’s not supposed to do it, but I like to leave a tip for the hotel … ”

While it is not common to see commanders-in-chief handling cash there have been some exceptions to the rule — dating back to the first US president.

A wallet belonging to George Washington at the Old Barracks Museum in Trenton, NJ, contains a 1776 two-thirds dollar bill and a 1779 one-dollar bill.

The night he was assassinated at Ford’s Theatre in Washington, DC., Abraham Lincoln was oddly toting a $5 Confederate bill and also had a wallet on him, according to the Library of Congress.

And in 1984, Ronald Reagan was spotted pulling out a $20 from his right front pants pocket to pay for a Big Mac, a large order of fries and a sweet tea at a McDonald’s in Alabama. He then pocketed his $17.54 in change, the Tuscaloosa News reported.

But most modern presidents are rarely seen carrying cash — since they don’t really have to.

“Everything’s provided for them — they really don’t need money,” presidential historian Thomas Whalen, of Boston University told the BBC in 2014.

Aides or Secret Service agents can loan president’s money if necessary.

Others, like John F. Kennedy, “didn’t carry any cash at all, even before he was president,” Whalen said.

“His friends would have to foot the bill for the privilege of hanging out with him.”

Still, some presidents continued carrying around credit cards during their tenures — and went through the embarrassment of seeing them declined.

In 1999, Bill Clinton had to borrow a couple of bucks from an aide when his card got rejected at a bookstore in Park City, Utah, the Deseret News reported at the time.

It’s unclear why Clinton’s card was declined, but when the same thing happened to Barack Obama at a Manhattan restaurant in 2014, he said it was because he hadn’t used it in so long.

“I was trying to explain to the waitress, you know, I really think that I’ve been paying my bills,” Obama joked. “It turned out I guess I don’t use it enough.”

“They thought there was some fraud going on.”

Luckily, then-First Lady Michelle Obama had a credit card on hand and paid for the couple’s meal.

During a visit that year to a barbecue joint in Austin, Texas, Obama tried to pick up the tab but “produced a wad of $20s for an order that came to exceed $300,” according to the pool report. He ended up paying with a JPMorgan credit card.

George H.W. Bush also apparently carried around a credit card and cash.

During a televised interaction in Arlington, Va., in 1991, an 8-year-old boy asked Bush to see some identification — and the then-president pulled out his green American Express card.

That same year, he was spotted paying for athletic socks in cash at a J.C. Penney in Frederick, Maryland.

Some 14 years later though, his son, George W. Bush told a Spanish-speaking journalist that he only had a handkerchief in his pockets.

“No dinero,” Bush said. “No wallet.”

The question to Trump on Wednesday was prompted by a Reuters photo of him boarding Air Force One, when a gust of wind revealed $20 bills hanging out of his pocket.

“Oh, that’s funny. So the jacket was blowing up?,” Trump said. “Boy, that’s a good picture. Hey, I’d like a piece of that picture.”

It’s unclear if Trump hands out $20s to every bellboy and receptionist at the hotels he visits — but he’s known to be a big tipper.

During a 2017 dinner at the Trump International Hotel in DC, he was spotted giving a $100 bill to a young busboy.