Good gravy is an expression that is often used to express surprise, astonishment, or disbelief. However, if you're looking for some synonyms to replace it with, you can try "oh my goodness," "oh wow," "oh my word," "oh dear," "oh dearie me," "oh gosh," "wowee," "wowza," "goodness gracious," "holy moly," "golly," and "holy cow." These phrases can convey a similar sentiment to "good gravy" and be used in various contexts such as expressing shock, excitement, or disbelief. So, the next time you're looking for an alternative to "good gravy," try these phrases and see what works best for you!