Informal a man of the S U.S., variously characterized as easygoing, companionable, assertively masculine, and strongly identifying with his regional lifestyle
See good old boy in American Heritage Dictionary 4
also good ol' boy or good ole boy
noun Slang
A man having qualities held to be characteristic of certain Southern white males, such as a relaxed or informal manner, strong loyalty to family and friends, and often an anti-intellectual bias and intolerant point of view.