In certain aircraft with 12 day trips, it is possible to sell your vacation back, then, if you have a carryover trip, bid to conflict with that trip, which will drop your one 12 day trip. Then elect 0 makeup hours. You have just been paid for your vacation, plus 24 hours, yet you didn't fly for the month (well except the carryover trip).

I am just theorizing that this might be a good way to have your cake and eat it too, not suggesting that anyone should actually do this.