The expression, “Good grief” is called a EUPHEMISM (pronounced: yew – fuh – miz – em). Euphemisms are words we say that are more socially acceptable than what we would otherwise choose to say. “Good grief!”, is an expression that means we are very irritated or upset about something. The “…grief” part of the expression refers to the emotional sense of being irritated or upset; grieving about what has happened. The “Good…” part of the expression is a reference to God which is intended to add emphasis and impact to the expression. Many people do not like to say the word God in public conversations so they often substitute the word “Good” instead.

“Good” and “grief” have their own separate meanings as words. But, in this case, the expression “Good grief” does not have a lot to do with the definitions of the individual words. It is simply a way of saying you are very upset about something.

Does this help?

For petes sake

For crying out loud

Jesus help me

All mean the same thing: Its a form of expression that you are irritated by something or someone and are venting release, instead of saying… Something really negative

Like : you studid idiot , get the picture? (not you, This is just an example)

Hope that has cleared things up.