Cowtown was a nickname given to Calgary, Alberta because it is one of Canada's largest beef-cattle producers. It's also a city full of good ol' fashioned cowboys.
Torontonian 1: "Man, I'd love to go to Calgary this summer for The Stampede"
Torontonian 2: "Ugh. You want to go to Cowtown?"
Torontonian 1: "Ya man, I want to wrangle me a Cowboy"