Good Gravy! is an exclamation of surprise or dismay. It is often used to express shock or disbelief at a situation. EGAD, EGADS, and OHNO are all interjections that are used to express surprise, shock, or dismay. EGAD is an abbreviation of the phrase 'Oh God!' while EGADS is an abbreviation of the phrase 'Oh God's Sake!' OHNO is an abbreviation of the phrase 'Oh No!' All three of these interjections can be used to express the same sentiment as Good Gravy!