How to get the fourth boss: when you get enough stars a purple icon should float around a song, you have to play three songs that the purple icon floats around, then it should direct you to i just wanna burn where you will meet the fourth boss
PLUSS SO OTHERS CAN SEE
i found something... click the sun then click the third lign then a cloud will come by wait until you see the left end and click it (to be more specific click the left end)
 "Super Villainy"){kind=icon}
 "Armed with Wings 3"){kind=icon}
 "SCGMD4"){kind=icon}
 "Lab of the Dead"){kind=icon}
 "Mr. Anderson: Amateur Sniper and Avenger"){kind=icon}
 "House Idle PRO"){kind=icon}
 "Idle Dancing"){kind=icon}
 "Johnny Rocketfingers 2"){kind=icon}
 "Escape from really boring island 2"){kind=icon}
 "Death Row"){kind=icon}
 "lololol pwn hair loss"){kind=icon}
 "Infectonator : World Dominator"){kind=icon}
 "Move Your Mouse"){kind=icon}
 "LOL, the sexy green button named sonny, episode 4"){kind=icon}
 "LOL, The sexy green button named Sonny, episode 1"){kind=icon}
 "The Funny Lightbulb Game"){kind=icon}