(verb expression) Short for locking the magazine/cartridge into the gun and loading the ammunition into the gun's chamber. (Usu. used to show toughness, ambition, fear and other strong characteristics. Originally spoken by John Wayne in "Sands of Iwo Jima" as "load and lock".)
One of the commandos in Resident Evil says "It's time to lock and load." when first seeing advancing zombies.