"If it works!"
The "Riker Maneuver" was the name informally given by Lieutenant Commander Geordi La Forge to a tactic used by Commander William T. Riker, in acting command of the USS Enterprise-E, to combat two Son'a battle cruisers in 2375. Following La Forge's suggestion that history would assign that name to the maneuver, Riker replied, "If it works..."
Attempting to elude the ships in the area of space known as "the Briar Patch," Riker ordered the Enterprise's ramscoops utilized to collect highly-unstable metreon gas. Upon filling the storage cells to maximum capacity, Riker activated the ship's manual steering column to perform precision maneuvering, and ordered the ramscoops released.
Riker then piloted the Enterprise in close proximity to the Son'a ships, leaving a cloud of metreon gas between them and the Enterprise. Subsequent to one of the pursuing vessels firing at the Enterprise, the gas ignited, destroying one of the ships and severely damaging and disabling the other. (Star Trek: Insurrection)
La Forge's comment may have been merely jovial. The maneuver is similar to a previously depicted incident in "Night Terrors" in which the Enterprise crew vented hydrogen into space to be ignited by another ship. However, in that case, it was not with the express purpose of damaging or destroying another ship in combat, and therefore would not have been classified as a "maneuver".
The movie script alludes to the joystick used by Riker as a computer gamester's dream.
Fans commonly refer to the unusual way Riker sits down in chairs (throwing one leg over the seat's back) by this name. 
The Riker Manuever is an ability available to certain playable variants of the Sovereign-class in Star Trek Online, through the use of metreon gas canisters specifically carried aboard the ship for this purpose.