One I'm proud of but might not be counted as a hack here (not exactly naughty, but good for blowing people's minds, so similarly satisfying to me): Amicable divorce without lawyers. Saved probably tens of thousands of dollars on lawyers fees and had the added bonus that since we didn't lawyer up, we weren't getting antagonistic "cover your ass" advice from lawyers. This meant there was more money to go around (and less paranoia), so we both were able to refrain from squabbling about the small stuff and say "whatever makes it easiest for you". I had people tell me I was crazy to trust my ex but I got a lot more money out of it than I otherwise would have (more than I could have legally insisted on had I fought with him).
We went to the courthouse together to file the papers. The person behind the counter was telling him "you need to do yadda yadda". I guess they thought I was his new love interest, not the future ex. He turned to me and said something like "Did you hear that? You need to sign here." I signed there while the person behind the counter tried to pick their eyeballs back up off the floor. I guess they had never seen anything like it before.