It’d been a frustrating series of mornings. Each day, I’d chugged down to the subway platform at Grand Central, only to find the 6 pulling away. So I decided to sit in the front of the 8:16; getting into Grand Central a minute quicker would help me make that elusive subway, the thinking went.

So I did. And sure enough, as I climbed down the stairs to the platform, the 6 was sitting there, doors open, waiting for me like a mother waits for her child after his first day of school.

I hustled across the platform as, alas, the doors began to shut. I got my foot in the door, then waited for the conductor to spring the doors open so I could slide in. He did, then pulled a maneuver I’d not yet seen in 15 years of subway riding: He slammed shut the doors with such supersonic force that they cut my hand and, like a nutcracker on my skull, bent my glasses. Within a split second, a platform monitor, swinging a flashlight like a truncheon, was on the case.

“SIR, PLEASE STEP OUT OF THE DOORWAY AND LET THE TRAIN GO!” she bellowed.

Defeated, I stepped back, as the 6 train mockingly pulled out of the station.

“What the f*** was that?” I asked her, but I knew she was right: If idiots like me didn’t jam their foot in the door, the whole system would run a lot smoother.

Still, didja have to bend my glasses?