Egg foo young (or egg foo yung, or egg fu yung...anyway, it's the Cantonese pronunciation) is a crispy pan-fried, or sometimes even deep-fried, omelet containing vegetables such as mushrooms, bean sprouts, and water chestnuts, and sometimes including meat such as chicken, cha siu, or shrimp. The Chinese-American version is usually smothered in gravy, because, America, giving it the chicken-fried steak treatment.
Personal Note
I only had this dish recently (just for this app) and didn't realize it's a real Chinese dish. I thought someone just made up the name.