heart in one's mouth, to have one's

To be frightened or extremely apprehensive. This term has nothing to do with eat one’s heart out but rather alludes to the heart-pounding and choking feeling of sudden fear. It was already used by Homer in the Iliad (ca. 850 b.c.), “My heart leaps to my mouth,” and appeared in English in Nicholas Udall’s translation of Erasmus (1548): “Hauyng their herte at their verai mouth for feare.” Mark Twain put it more colorfully: “My heart flew into my mouth so suddenly that if I hadn’t clapped my teeth together I should have lost it” (Life on the Mississippi, 1874).