(Washington State Patrol)

By most measures, the traffic stop was an ordinary one: A Washington State Patrol trooper pulled over a driver Tuesday morning for an HOV lane violation.

What was unusual? The driver had a larger-than-life cardboard cutout of Donald Trump’s head affixed to the passenger-seat headrest.

State Patrol spokesman Rick Johnson said he couldn’t help but laugh — and post the photo on Twitter.

“WSP Motorcycle Trooper Greg Ulrich stopped a vehicle this morning NB 167 in Auburn for violating the HOV lane,” Johnson tweeted. “Do you know why?”

Within minutes, the tweet took off.

People had jokes, it seemed — including at least one inspired by the first presidential debate between Trump and Hillary Clinton.

“I’m sure he’s insisting he did in fact not violate the HOV rule,” one tweeter responded. “Just call Sean.”

Noted another tweeter: “airbags don’t count as passengers.”

How much was the driver fined? “A YUGE amount,” read one response.

In fact, the driver was cited and fined $136, the normal amount for an HOV violation, Johnson told The Washington Post.

Johnson said he and Uhlrich, who both have about 25 years on the force, have previously stopped other HOV lane violators who kept mannequins or other cutouts in the passenger seat.

But Trump’s head was new.

Now, Johnson said, “we’ve seen it all.”

Read more:

Winners and losers from the first presidential debate

Trump says he may hit ‘harder’ in next debate; Clinton tells reporters she had a ‘great, great time’

A quick guide to getting That Presidential Look