He just did. When it gets hit with sufficient amounts of adrenaline, or is sufficiently messed up chemically, the body can force itself to do things that would normally be impossible. It's like how every weightlifting crane tells you it can take a certain load, but that's actually just what the safe rating is, where the machine can operate without experiencing mechanical stress. The human body is exactly the same, and in some circumstances, the safety rating is disengaged. It's part of the reason why sleepwalking is so dangerous, because the brain isn't operating properly and many of those autonomic safety ratings aren't engaged. People can do themselves horrible, permanent injuries casually lifting things their pain thresholds would normally tell them not to even attempt, shearing muscles off bones in the process, all while their brains cheerfully slumber on. Or they find locked doors in their sleep and break through windows instead, dying of massive arterial bleeding from the cuts they sustain smashing and then clearing the glass with their bare hands. It's pretty amazing what won't wake somebody up when they're in such a state.
In this case it was a simple matter of a dangerous psychotic wigging out during an interview. Hospital thought he'd been heavily sedated and stuck him in a room in 'only' metal handcuffs and an sheet of inch-thick Plexiglas between him and a young, pretty intern. Then the Ocelot God started whispering to him, and religious fervor did the rest. Sadly I don't know exactly what damage he did to himself, but I'd imagine that ripping off the cuffs gave him pretty serious lacerations, and the trip through the glass didn't improve his complexion. But he held it together long enough to give my friend some pretty noteworthy scars and a persuasive argument as to why psychology probably wasn't the best career choice.
