Role-play fighting. Usually done on "RP" forums or chatrooms where two characters from their own RP world, controlled by those very two people from the real world pretty much duke it out. They define who wins and how amazing the fight can be.
Of course, finding someone who can be a 'fun fight' can prove difficult at times.
Guy1: Hey, wanna RP fight?
Guy1: *Pulls out Buster Sword* Let's do this then.
Guy2: *imeditly throws 100000 lite sabrs at u an chops u in a milin peesis an casts a spel so tat u ded 4ever and can nevr cum bak frum teh ded an i win teh fite. then blws up erth so u cant breeth if by sum chenc u do cum bak wich u wont*
Guy2: ye i alwys win. tis so ez 2 pwn in. who next la?