Boarding passes are full of data about the passenger who is holding them, not just about where they plan on travelling to.
While most codes printed on your boarding pass are harmless, there is one that may indicate bad news for you as a traveller.
According to an Air Canada ticket agent, there is one code you don't want to have on your boarding ticket - "GTE".
If you have GTE on your ticket it reveals your flight has been oversold.
"If someone has GTE (for 'gate') on their boarding pass, it means they don't have a seat," the ticket agent worker told CBC.