Ecphonesis
Ecphonesis (Greek:ἐκφώνησις) is an emotional, exclamatory phrase (exclamation) used in poetry, drama, or song. It is a rhetorical device that originated in ancient literature.
A Latin example is "O tempora! O mores!" ("Oh, the times! Oh, the morals!"). A modern example is "Young man!" from the song YMCA by the Village People.