My big toe nail fell off, what am I supposed to do?

clean it and cover it

Omg don't clip it until it grows all the way to the tip, you are so lucky if you don't mess with it because the pink part will probably grow all the way to the tip of your toe, and then after that will be the white part that you have to clip!!! Long toe nails are sexy, as long as its not gross and white!!! But if you clip it before it grows all the way, the pink part will probably stop growing and it will grow white and ugly from there. Good luck!!!!

Sell it on eBay

Mine did that when I hit it and it went black because it bled underneath. 

All you do is wait. A new one will grow back. 

To that other user: shut up and stop spamming your dumb bullsh*t because you're not a f*cking health professional & don't know what you're talking about. Anyways, keep the area clean and apply antibiotic cream to the area, then apply a bandage to it. Also make sure you change the bandage everyday. 

Super glue?  Seriously, it will grow back.

See a doctor.