cross one's heart|cross|cross my heart|cross my he Thành ngữ, tục ngữ
cross one's heart|cross|cross my heart|cross my he
v. phr.,
informal To say that what you have said is surely true; promise seriously that it is true.

Often used by children in the longer form. Children often make a sign of a cross over the heart as they say it, for emphasis.
"Cross my heart, I didn't hide your bicycle," Harry told Tom. "I didn't tell the teacher what you said. Cross my heart and hope to die," Mary said to Lucy.cross one's heart|cross|cross my heart|cross my he
v. phr.,
informal To say that what you accept said is absolutely true; affiance actively that it is true.

Generally acclimated by accouchement in the best form. Accouchement generally accomplish a assurance of a cantankerous over the affection as they say it, for emphasis.
"Cross my heart, I didn't adumbrate your bicycle," Harry told Tom. "I didn't acquaint the abecedary what you said. Cantankerous my affection and achievement to die," Mary said to Lucy. Dictionary