Challenge your friends to sit the egg up. They won't be able to, unless you show them the secret!
During printing, you will need to drop a ball-bearing into the center of the egg. anything from 10 to 14 mm diameter should work. Make sure you drop it in far enough into the print that your print head will not collide with it.
Monoprice PLA Plus
You can sand the egg down with a sanding sponge if you wish to have a nice smooth finish. Sanding looks great in white, but this will slightly expose nooks in your print surface.