To cut ones eyeteeth

from The Collaborative International Dictionary of English v.0.48

Eyetooth \Eye"tooth\ ([imac]"t[=oo]th`), n.; pl. {Eyeteeth}
   ([imac]"t[=e]th`) (Anat.)
   A canine tooth of the upper jaw. See {Teeth}.
   [1913 Webster]

   {To cut one's eyeteeth}, to become acute or knowing.
      [Colloq.]
      [1913 Webster]