holy cow
US /ˈhoʊ.li kaʊ/
UK /ˈhoʊ.li kaʊ/

1.
an exclamation of surprise, astonishment, or excitement
:
•
Holy cow, I can't believe you actually won the lottery!
•
When he showed me his new car, all I could say was, "Holy cow!"
an exclamation of surprise, astonishment, or excitement