Complicity is involvement in a wrongful act — like when you drove your newly-turned-vegetarian friend to a fast food joint so that she could scarf down a hamburger.
Complicity refers to the act of helping someone else behave inappropriately or illegally. If you find yourself accused of complicity, it's often helpful to show that you were unaware of the other person's intentions. In the case of the trip to the fast food restaurant, that's going to be hard to prove. You'll probably be scorned for being an accomplice, or someone who is complicit, in your friend's shameful act.
