It's often used in a lighthearted way, even when expressing frustration.
Origins:
While the exact origin is unclear, the expression likely stems from the name "Betsy" being a popular name in the United States during the 19th century. "Heavens" is a reference to the sky or God, adding a touch of religious undertone to the exclamation.
Example Usage:
* "Heavens to Betsy! Look at the size of that spider!"
* "Heavens to Betsy, I forgot to buy milk again!"
* "Heavens to Betsy, that's the third time I've tripped over that rug!"