Not to my knowledge. Would like to see some theories.
My best guess about 'insert_key' is that it is related to Q post #11:
>Key:
>Military Intelligence v FBI CIA NSA
>…can the President impose MI take over investigations for the 3 letter agencies?
>Why is this so VERY important?
But my first thought was of #157:
>What is a key?
>Who unlocked the door of all doors?
Another interesting possibility was Q's reply to the question 'What can you tell us about Assange??' in #3341:
>Key to DNC 'source' 'hack' '187'.
Or if going by Q's first use of the term, there was this in #3:
>It finally came out that Rod/Bob were key players in the Uranium scandal.