JoeCo is correct. It comes from a comedy series called the Second City Television Network with the dynamic duo of Bob and Doug McKenzie. The series of skits was called the Great White North. Where Bob and Doug were often heard to exclaim "Take Off Eh!, Ya Hoser!
Also, the reason why Canucks say 'Eh' all the time is derived from the way our countries name is spelled:
C-Eh-N-Eh-D-Eh!
Cheers Eh! OffshoreIgor
