One of my biggest pet peeves is when I think of something brilliant that already exists. It happens to me all the time. Some would say, "maybe your ideas aren't that brilliant." Unlikely. Maybe too many things exist. My latest stroke of genius proves it.
Have you ever hated someone so much you wish you could shit on their face? Me too. That's why I invented George W. Bush toilette paper. I even had a tagline "Wipe away that stupid smirk." The only problem is, someone already invented it. Figures.