Eating 5 oranges per day is actually good for you and nothing bad will happen to you if you do eat 5 oranges per day.
Oranges are a great source of several vitamins and minerals, including vitamin C, thiamin, folate and potassium which is all beneficial to your health and can protect you from viruses and boost your immune system.
If you're trying to lose weight though than eating 5 oranges everyday could cause you to gain more weight instead of lose weight even though oranges are pretty low in calories but the calories can add up.