A few miles down the highway, something started to go "screeeeeeee."
"Jeff," I said, "your window might be a little open."
Thankfully, he was buckled in, because his reaction was to open the door, at 65mph. His reflexes worked. He pulled it closed. And the screeeeeeee got louder, at which point I realized his knee was hitting the window crank. I pointed this out and, remarkably, he tightened it. No more screee.