What is ovo vegetarian ?
It's basically vegetarianism but you can eat eggs and not dairy.
Really?
Yeah, in contrast with lacto vegetarianism which is the opposite.
Why are people ovo vegans ?
They see more morality to eating eggs than they do eating dairy products.
lol. Really funny 
They're also called that because ovo means egg in latin.
Good to know
They are even called eggetarians by some, since ovo vegetarians revolve around eggs.