Raktajino
From Memory Alpha, the free Star Trek reference
Raktajino (pronounced rack-tə-jeen-oh) is Klingon coffee, served steamed or iced.
Raktajino wasn't known in Federation facilities such as Deep Space Station K-7 until sometime after 2268. (DS9: "Trials and Tribble-ations")
Jadzia Dax and Julian Bashir drank raktajino occasionally. In 2369 they were sitting at the replimat and doing repairs during the absence of Chief Miles O'Brien. Bashir asked Dax if she would like to have another one but Dax said that this would keep her up all night. Bashir then answered he knew better things to keep her up all night than Klingon coffee. (DS9: "Dax")
The beverage was eminently popular with the Starfleet members on Deep Space 9 in the 2370s, the senior staff in particular, Jadzia Dax and Julian Bashir for example ordered two raktajinos, extra strong, in 2369. (DS9: "If Wishes Were Horses") Major Kira also drank raktajino occasionally. (DS9: "Duet")
Benjamin Sisko started every morning off with a raktajino; in fact, he was not awake, much less did he talk to anyone until he had his first cup. Sisko also enjoyed drinking his raktajino with jacarine peel; this drink also went well with icoberry torte. During 2373, however, Benjamin was trying to cut back on his consumption of raktajino. (DS9: "Second Sight", "The Homecoming", "Children of Time")
Both Curzon and Jadzia Dax enjoyed raktajino, with Jadzia occasionally enjoying hers as a double raktajino, extra sweet or iced with extra cream. (DS9: "The Passenger")
While Ezri Tigan hated the beverage, once she was joined with the Dax symbiont she was unable to control the urge to drink it. (DS9: "You Are Cordially Invited", "Shadows and Symbols")
Raktajino has the properties to intoxicate Talarians. (DS9: "A Simple Investigation")
Tom Paris enjoyed raktajino with whipped cream on top; he considered ordering the beverage with his extra replicator rations. (VOY: "Meld")
During the Dominion occupation of Deep Space Nine of late 2373 to early 2374, Mavek brought Kira Nerys a raktajino every morning. (DS9: "Rocks and Shoals")
