Eggs:

Pizza gun:
There are 3 pizza boxes around the map, once you get all of them a weapon is revealed behind jugg

Soulbox:
Grab the skull next to ICU, place it in showers(phd) and get 115 kills close to the statue

After this you can get:
Wavegun, in bunker
Paralyzer, in ICU room
Skull of nan on the island, buyable ending and buyable to unlock retreiver is also there