As you enter SCP-173's containment chamber, you notice 173 staring at the wall. Suddenly, it rotates into your line of sight.

You must not break your line of sight. This includes walking away or blinking. If you do, it can go near you at fast speeds. If it manages to reach you, it will snap the neck at the base of the skull, or by strangulation. The presence of 173 can force you to blink.