How to turn this simple game from "meh" to "lol":
Try incorporating something funny, instead of a basic "metal edge pops bubble." The first thing that popped in my head is a top down view of a creepy guy who hates people, stumbling around trying to avoid a crowd of people. Maybe he's antisocial, maybe they wanna beat him up. Either way, replace the bubble with a guy, and the edges with a crowd of people.
Another idea would be to make it a "Mosh Pit Survival" game, where instead of the bubble you're a guy trying to get out of the mosh pit, or at least survive until the end of the song. Yeah! Let the timer be a segment from Newgrounds songs! (Use Final-Round songs, btw) :) [final-round.newgrounds.com/audio]
I hope these ideas help you with future projects. Keep them coming!