Photos: 99 Portraits for the 99 Percent

Most of us walk around following unwritten rules even if we’re not aware of it. Maybe it’s a common social custom we mistakenly assume everyone else cares about. Perhaps it’s an office policy that doesn’t technically exist. But every so often you meet someone who seems to follow their own code, causing you to rethink what’s obligatory and what’s optional.

That’s the basic premise of a recent online thread where someone asked the intriguing question, "What’s something you always assumed was mandatory in life—until you met someone who just…didn’t do it?" The responses seem to tackle every aspect of life, from work to casual conversation.