Which airport has the call sign YYZ?

Well, the first Y is because every Canadian airport starts with a Y. The obvious YTO is already taken for Toronto as a City, for bookings to Toronto (All Airports), like London (LON), has loads of different airports (LHR, LGW, LCY, STN, LTN, LSO). The YZ is just random. Some people say its the code for a weather station that is at the airport, so they use that. Others say that in the village where the airport is there is a radio mast with that code, so again they just used that. Hope this helps!