Straight dinkum

My precious, please don′t ever send me a penny of extra money. That is very straight dinkum.

“Say, cross my heart straight dinkum.”

This morning, I promise cross my heart straight Dinkum (is that right?) will be the last, the very last, of our awful moments.

[…]she said scornfully, “One of the girls gave it to you. Tell me at once who it was.” “Cripes, no, straight dinkum. I just picked it up.”