You can't just ask somebody to stab you and refuse to explain.

She nods, her hands clasped together on the tabletop. It's another thing people don't really have to say--not these days. After two years, you know how walkers work, or you're dead. "If you die and nobody does anything about your brain, you become a walker. Doesn't matter if you were bitten or not."

At least they've already gone over those. Even if he was drunk then (or pretending to be drunk? who knows?), he has to remember the walkers. Remembering the headless corpse being carried away, she adds, "We should probably start stabbing everyone in the head, just in case."