I can't think of any reason to utter "gyu" as an exclamation instead of a normal word, so I'm going to assume she was about to start some sort of cow-themed insult since there are very few words that start with that sound that aren't cow-related and all of them make even less sense.
Just to whomever did a slew of down-voting to these comments:
These comments are harmless, constructive and funny; there is nothing "down-vote worthy" about them.
Calm your own cow tits down instead.
cow-t...Just die already.Flan… this is the doctor who will heal youNow listen, you must not be rude to herHmmmShe showed up naked...Sister… who is this person?
