Last week, residents of Arlington, Virginia, were stunned to see an unmarked, gray Ford Transit van tooling around town without a human driver behind the wheel. According to ARLnow, the vehicle was spotted driving through the Courthouse and Clarendon neighborhoods with nary a soul in the driver’s seat. Some speculated the van was part of Virginia Tech’s recently approved autonomous driving tests, and were content to leave it there. But then the story got even weirder.

On Monday, NBC 4’s transportation reporter Adam Tuss spied the driverless van again at a stop sign. And when he approached, Tuss noticed the driver’s “seat” had two hands and legs sticking out from it. Tuss tried to get the costumed driver to talk, but they sped off, running a red light in the process.

Here's me trying to talk to a man in a car seat costume @nbcwashington pic.twitter.com/e5humOM7uS — Adam Tuss (@AdamTuss) August 7, 2017

So not only does Virginia have self-driving cars, it also has vehicle’s driven by people dressed up as car seats, too. Tuss was unsuccessful in getting the “car seat” guy to talk to him, even using the “I’m with the news, dude” line that all serious journalists employ to persuade reluctant sources to talk. (I’m not dragging Tuss, I promise. I just found that line super hilarious and I’m going to start using it now all the time.)

ARLnow reached out to the local authorities, who couldn’t confirm the vehicle owner’s identity, or why anyone would be dressed up like a car seat. “ACPD is aware that driverless vehicles are being tested in the Commonwealth,” a spokesperson for the county police told the outlet. “Officers have not had contact with the vehicle observed in Clarendon. If officers observe a traffic violation, they will attempt a traffic stop.”

So it’s most likely that this was a prank of some kind — a very weird prank. Experts on autonomous vehicles noticed a light display behind the van’s windshield, as well as the presence of some cameras, which would seem to indicate that there was some driverless testing going on.

video from last week, so it's likely that it still was a test of AV software in some form. 2/2 https://t.co/QKDSuBqp6E — Greg Rogers (@gregoryrrogers) August 7, 2017

If this was indeed an autonomous vehicle test, why hide the safety driver? Practically every self-driving vehicle on the road today — whether its operated by Google, Uber, or a major automaker — still has a human driver behind the wheel. And they don’t go to the ridiculous lengths to disguise the driver from the public. People are still very much skeptical about self-driving cars and most aren’t ready for the psychological shift that will accompany the transition to driverless cars. Many engineers and operators openly discuss the challenges ahead in convincing the public that autonomous vehicles will be safer and more efficient than human-driven ones.

If this was some sort of psychological experiment to gauge pedestrians’ reactions to a “driverless” vehicle, it was pretty poorly managed. My heart goes out to the poor research assistant embedded in that car seat in such humid weather. What a terrible summer job.

Updated August 7th, 6:03 pm ET: Mystery solved! After multiple inquiries by NBC 4, Virginia Tech’s transportation institute finally copped to the weird display, acknowledging it was part of a study on driverless vehicles. The driver was wearing an outfit meant to minimize his visibility.

"The driver's seating area is configured to make the driver less visible within the vehicle, while still allowing him or her the ability to safely monitor and respond to surroundings," the institute said in a statement to the channel.