To the Secret Service, George H.W. Bush was “Timberwolf” — but it took a trip to New York and a creative NYPD detective to come up with a proper phrase for him when nature called.

Then-Detective Kerry Breen was among the NYPD contingent escorting the former president’s motorcade to the Bill Clinton Global Initiative event in Manhattan in 2010.

At one point, Breen heard a Secret Service agent holler, “We need to stop at the Port Authority building — Timberwolf needs to take a piss!”

“I was slightly annoyed by this semi-crass description of a bodily function for a war hero, former president and seemingly elegant elderly man,” Breen, who is now retired, remembered to The Post on Sunday.

“When the agent returned to our car, and the ‘package’ [H.W. Bush], the line of cars, was under way, I suggested to the agent a better descriptor of the exigency,” Breen said.

“’Hey, if he needs to go again, how about you just say, ‘Timberwolf needs a tree?’ Breen recalled saying.

“That day, I unknowingly coined a phrase,” Breen said.

At least two years later, the Secret Service was still using it.

“Odd thing to be proud of,” Breen said, “but I remain so.”

Of Bush himself, Breen said, “He was a charming fella.”

Bush died Friday at age 94.