cross heart

cross my heart (and hope to die)

A vow that one is being truthful. Billy's the one who broke the cookie jar—cross my heart and hope to die!See also: cross, heart, hope

cross one's heart (and hope to die)

Fig. a phrase said to pledge or vow that the truth is being told. It's true, cross my heart and hope to die. It's really true—cross my heart.See also: cross, heart