The kapow t-shirt was created as a way to vent pent up rage in a discreet manner. Irony was the delivery method of choice, using powerful words in a very small font. The bright colour of the shirt helps deliver the over effect.
Some people have likened it to the fighting words of the old Batman TV series, which was not my intention, but still, I can see their point.
I am intending on creating some other shirts in a similar vein one day.