As a matter of fact...
I'm not a DBZ fan by any definition of the word, so if I missing some underlying context to this that's why. However it's just plain funny.
This is a case of taking one line from a show (a particularly retarded line for that matter) and creating a running gag of sorts -- except there's no plotline for the gag to run over (the gag is the plotline).
All I have to say is this: "His stupidity is beyond belief!"