…context is everything when it comes to boasting. If Avi's friend raised the topic of the exams, Avi received favourable ratings in terms of his boastfulness and likeability, regardless of whether he was actually asked what grade he got. By contrast, if Avi raised the topic of the exams, but failed to provoke a question, then his likeability suffered and he was seen as more of a boaster. In other words, to pull off a successful boast, you need it to be appropriate to the conversation. If your friend, colleague, or date raises the topic, you can go ahead and pull a relevant boast in safety. Alternatively, if you're forced to turn the conversation onto the required topic then you must succeed in provoking a question from your conversation partner. If there's no question and you raised the topic then any boast you make will leave you looking like a big-head.
There is more here. Have you ever wondered, by the way, why I ask for topic requests so often?