Monkeyshines!

To get your score up to 99 in one go, you must be playing on a level with no horizontal bars on the side of the screen. You can program a level like this yourself. Go to the top, then tag a monkey against the wall diagonally down from you. Keep holding down the button and you will continue to tag the same monkey faster and faster. When you reach the bottom your score will get up to 99.