(1)A stupidathon is when you're on a role doing stupid things.
(2)When you are walking along, possibly at school, and you see two groups of people hurling the most retarded instults back and forth.
I saw two people having an argument, and in the end they both kept saying cliche terms like "Is that all you got?" or "Can't you think of anything else?"
They were having a stupidathon