Once everyone knows when you are going to do it just stand up and yell FOOD FIGHT and throw your lunch at a … If the food fight is going to be outside, fill balloons with soda or fruit juice. you wanna spread the word that you are starting a food fight. Note: You will most likely get the Sharing is Caring achievement while seated at the table with other players performing your "FOOD FIGHT!" Fill … Hit any food button available to you and start throwing food at them, after a minute you should get the "FOOD FIGHT!" Water balloons are fun no matter what they are filled with.