What is an equivalent Portuguese expression for "to have eyes on the back of one's head"? (reference) The phrase is often used to express surprise that an action was observed by someone else.
Example: How did you know it was me? You must have eyes on the back of your head.
There is a simpler expression in Portuguese:
Ter um olho na nuca.
Although when literally translated this seems to mean to have an eye in the nape/scruff (related to the back part of the neck), the intended meaning is to have an eye in the back part of the skull.
(Apologies for the creepy image) Here's a few references where this expression is used:
