eyes in the back of one’s head, to have

To be exceptionally alert. This expression dates from Roman times, appearing in Plautus’s play Aulularia (c. 210 B.C.) and cited by Erasmus in his collection of adages. Put slightly differently, it appeared in John Still’s play Gammer Gurton’s Needle (c. 1565): “Take heed of Sim Glovers wife, she hath an eie behind her!” (2.2).