Said to confirm that what you said is completely true. This expression is used mainly by children, without knowing about the solemn significance of this religious oath

"Cross your heart you're not gonna tell anybody!" "I'm not gonna tell anybody, cross my heart and hope to die!"

"Giura che non lo dirai a nessuno. Giura!" "Non lo dirò a nessuno. Che possa morire in questo momento!"

Mom, I'm going out to play for five minutes and then I'll be back right away to do my homework. Cross my heart and hope to die!

Mamma, esco a giocare cinque minuti e poi vengo subito a fare i compiti. Giurin giuretta!

This expression originated as a serious religious oath uttered by Christians