A rebel is a person who stands up for what they think is right, or just their opinions, regardless of what anyone (often their authorities) think. It's about not following the crowd and going through the everyday motions. They are usually outspoken and straightforward, meaning they don't care what others think and will tell off anyone. However, there are exceptions; some rebellion is just through passive-agressive actions (i.e., Ghandi). Rebels aren't non-conformists such as those they would define as "Gothic" or "Emo;" If they don't conform, it's because they actually think conforming to the situation and not speaking out is morally wrong. Being rebellious isn't something you do by choice, you're born with it.
The founders of our country were all rebels in one way or another, and they defied Great Britain, and against all odds, won.
Often a nice way of calling someone a douche, because they're honest and straightforward, regardless of how it sounds or who it offends.
Most people who have this quality are politicians, debate-club members, douches, or rebels.
Flirty Girl - Why don't ever talk to me? You're so shy! *wink*
Outspoken D-Bag - I'm not shy, you're just a slut, desperate for attention, who I wouldn't give five minutes of my day to 'cuz I've got a girlfriend.