First thing that comes to mind that I just did tonight...I stumbled across a probability "paradox", noticed that it had an infinity in it, got suspicious, expressed it in a form with finite population size, and took the limit as the population size went to infinity, and what do you know... the paradox vanished in a puff of canceling fractions.
As in Joshua Blaine's original description (below), but may be used to brag about things you've accomplished either this month (December) or the previous one (November), assuming that you haven't brought it up in any earlier Monthly Bragging Thread.