CBA = Can't Be Arsed.
CBA is a severe form of laziness.
Often comparable to a psychological/medical condition. CBA is most common in teenagers around the age of 16-17 years of age.
Person 1: You coming?
Person 2: Nah, I've got a severe case of CBA.
Person 1: What's wrong?
Person 2: I'm suffering from a chronic case of CBA.