The principle is simple: lots of people in Snuggies + Bar = comedy good. The first event was held in Cincinnati, Ohio on January 30, 2009; now they are worldwide. How many drinks before your first Snuggie pub crawl? I'd bet quite a bit.
Implications - The Snuggie pub crawl concept is a hilarious one but not completely unexpected after the Snuggies for pets concept. The concept is that by bringing people out of their homes and into the bars with the Snuggies comedy would ensue. I think the concept succeeded.