•You'd get money for losing the lottery
•You would get good grades for not doing you school work
•The less sleep you got the less tired you would be in the morning.
•Everyone who was dead would be alive.
•You could drive if you were under the age of sixteen.
•Candy would be good for your health.
•We would know what's going on until someone explained it to us.
•We'd be smart without going to school.
animals could talk.
•If convicted of a crime you'd be guilty until proven innocent.
•It would take more muscles to smile than to frown.
•The Hunger Games would be a bad book
•you would sleep at school/work
•everyone who was alive would die.
•brown would be a cool color.
•All of your friends would hate you.
•we would lose the ability of speech.
•we would spend more time at school/work than at home
•There are so many opposites it would be literally impossible to compare them all.
•There would be no way of organizing an opposite day because saying it's opposite day means its not opposite day but that means it is opposite day and so on and so on.
•If one person didn't know it was opposite day it would mess up the entire system.