A buffoon is someone whose ridiculous behavior is a source of amusement to others. People you might call a buffoon are a political rival or the guy at work who tells silly jokes at office parties.
The noun buffoon has changed its spelling over the years, but not really its meaning. In Middle French, it was bouffon, which came from the Italian buffone, meaning "jester." The original root is the Latin buffare. Think of the stereotypical court jester, the person who makes jokes and falls about trying to make the king laugh — he's paid to be a buffoon.