You can sign a union card if you are working at the University of Waterloo as a:
The Committee to Organize uWaterloo is a grassroots campaign to unionize the academic workers at the University of Waterloo. The campaign is supported by the Canadian Union of Public Employees (CUPE).
With over 700,000 members, CUPE is Canada's largest union. CUPE represents 70,400 workers spanning 233 collective agreements in the post-secondary education sector.