Okay just before you go to black mesa east there is a small warehouse with the Northeren Petrol symbol on it where oyu defeat the helicopter well go behind the warehouse and theres two sewage pipes one is closed and one is open either noclip or stack some stuff up to get inside theres radioactive waste so dont linger. go all the way down and theres a vortigaunt doing a weird chanting noice and he is rosting a headcrab on a stick! they eat headcrabs! if you wait long enough he tells you that nutmeg is a good ingrediant to have when eating black headcrabs LOLZ ROFLCOPTER!