Krabby Patties can be used to unlock new Power Players and locations as well as buy Boosts before each session.
You can get Krabby Patties by tapping Krabby Patty bubbles, bursting multiple bubbles during game play, and when you level up or beat your weekly/monthly/all time high score.  Krabby Patties can also be purchased from Selection screen by tapping “+” in front of Krabby Patty icon, or selecting “Add Krabby Patties” option from the menu.