1. In the ten years we owned that house, we were never able to get it into good repair. We poured money into it hand over fist, but nothing helped.
2. Paul’s candy was such a success at the fair, his stall was always busy with buyers. He was taking in money hand over fist , faster than he could count it.

The expression is usually used with money. It suggests that one draws in a fist full of money while the other hand is being extended to gather in more money in a continuous motion.