a) any type of goal was achieved
b) something more than expected happened or was obtained
Better when presented in the form of a question.
person A: So i picked up a blank tile and spelled 'QUIZZIFY'
person B: Bonus Bingo?
When talking to a friend after cleaning the house;
person A: So i picked up a broom and swept under the couch, and found a whole piece of pizza
person B: Bonus cheese?