I'll bite. While travelling about 95% of the year for work, I amassed a great number of travel vouchers on UA for various travel disruptions. While surfing the net I found a particularly lucrative fare which could get me ~65k in just a few days. Long story short, I took a week vacation from work, flew a few 22 hour days in that week, and cashed in some IHG pointsbreak nights, all to get some more of those previous miles. Total cost was some food and drinks, cab fares, and a nice pair of noise cancelling headphones (lifesavers).