Titan's Turn was a maneuver performed in the space above Saturn's moon Titan. Officially the maneuver was discouraged by Starfleet due to the danger involved, but over the years a number of Starfleet shuttlecraft pilots have performed the maneuver.
The maneuver involved the pilot accelerating directly towards Titan, and brushing against the atmosphere. At the last minute the pilot would turn the ship away from Titan. As a result the shuttle would whip around the moon at .7 c. And as the maneuver was discouraged by Starfleet, pilots would often, as Edward Jellico put it, pray like mad that no one saw them performing the maneuver. (TNG episode: "Chain of Command, Part II").