I am truly not sure why you're friend is putting the raw egg into water, unless he believes he is making the dog a shake.
but raw eggs are good:
Raw eggs are a wonderful source of protein, essential fatty acids Vitamin Bs and calcium when fed whole, including the shell. Some manufacturers coat the egg with a waxy substance to maintain freshness. If that is the case, do not feed the shell to your pet.
I feed my dogs all raw eggs in there ruffage as well
"In order to really enjoy a dog, one doesnt merely try to train him to be semi human. The point of it is to open oneself to the possibility of becoming partly a dog."