I love doing this at places outside of the South - looking for people wearing Tennessee stuff.
I went to Europe earlier this summer and wore a Tennessee polo one day, think we were in France. It didn't get any reaction but I noticed a lot of other college apparel over there - Florida, Oklahoma, Miss St, Virginia Tech, Texas A&M, Baylor, Texas, Georgia, Vanderbilt (yes, I was keeping track). No Alabama.
I was also in Boston last year visiting and wore an orange polo with the Power T on it. I ran into about 5 people from Tennessee who commented on it, and while walking down the sidewalk a Boston cop sitting in his patrol car with the window down started singing Rocky Top. It was awesome