There are two ways you can earn the quest one hundred freaking million.
1. Open your computer in the morning, play the game, cover the ground with ground saws so the combo won't stop and let it comboing until you get a 100.000.000 combo.
2. Start playing the game in the evening and let your computer open all night long. When you wake up, you will propably have reach 100.000.000.
Sorry for bad grammar.