Short for "Mark One Eyeball". Refers to using unaided vision to spot something, as opposed to binoculars, radar, etc. Commonly used by military internet know it alls to confuse people in an argument.
Actually you could overwhelm a CBG's defenses with about twenty five small craft attacking from all points of the compass due to the in ability of Ageis to lock onto a small target effectively in the sea clutter. Most confrontations in the Persian Gulf have been observed and started by lookouts using the MK1 eyeball.