Rest and Relaxation (often abbreviated to R&R) was a short vacation given to members of a military force.
In 2154, Jonathan Archer suggested that Hoshi Sato take some R&R in Norway or Canada after the Xindi crisis had been averted. (ENT: "Zero Hour")
The Starfleet crew of Deep Space 9 often took R&R in Quark's. The concept was alien to Tosk, as he felt that the Alpha Quadrant had too much "down" time. (DS9: "Captive Pursuit")
After he was assigned to the former Federation colonies in the Demilitarized Zone, Calvin Hudson had hoped to spend some R&R time with his old friend Benjamin Sisko, but, as Sisko himself pointed out, "Who's got R&R time?" (DS9: "The Maquis, Part I")
In 2374, Admiral William Ross was motivated to spend his next R&R on Bajor, following Benjamin Sisko's descriptions of the planet's beauty. (DS9: "Favor the Bold")
After talking to many people on the USS Defiant later that year, Captain Lisa Cusak suggested that the crew could use some R&R. (DS9: "The Sound of Her Voice")
In 2375, after Rom told him Grand Nagus Zek was missing, Quark suggested that he may be having "a little rest and relaxation" on Risa. (DS9: "The Emperor's New Cloak")