Like balls in a cup, maybe this contest needs "a bit more freedom."
With that in mind, make a random comic with 1, 2 or 3 panels (or a whole frickin' series with any number of panels, if you like) and include the phrase...
" and that's why I wear underwear "*
*As a bonus, you may substitute any form/kind of undergarment in place of the word "underwear": boxers, briefs, panties and so on, etc.