When you are in a battleground, and a member of the enemy team "rage quits", or leaves the battleground before the battleground has finished, you gain a "tear".
You are collecting the "tears of your enemies" :P.
Karma is a point system, users can give eachother positive karma +1 point, or negative karma -1 point. It helps you determine if a player is a person who you would want to play with.