What happens if I poke my eye with something sharp?

Wide range of things. Anything from an abrasion of tissues that heals without permanent damage to blindness from a penetrating injury due to infection. Bleeding in the eye, cataract formation, and corneal scarring are common from sharp injuries. See an eye md emergently for such an injury.
Nothing good! Traumatic abrasions, lacerations and perforations can result! wear your safety goggles!