If I seem to boast more than is becoming, my excuse is that I brag for humanity rather than for myself.

Every other enjoyment malice may destroy; every other panegyric envy may withhold; but no human power can deprive the boaster of his own encomiums.

If I cannot brag of knowing something, then I brag of not knowing it; at any rate, brag.

Mere flimflam stories, and nothing but shams and lies.

There is also this benefit in brag, that the speaker is unconsciously expressing his own ideal. Humor him by all means, draw it all out, and hold him to it.