knife
from the episode "Objects in Space"
Zoe Washburne:"Where's River at now?"
Captain Malcolm Reynolds:"In her room, which I'm thinking we bolt from the outside from now on."
Wash Washburne:"That's a little extreme, isn't it?"
Jayne Cobb:"Anyone remember her coming at me with a butcher's knife?"
Wash Washburne:"Wacky fun."
Jayne Cobb:"You wanna go little man?!"
Wash Washburne:"Only if it's someplace with candlelight."