Luck was believed to be, according to the Eleventh Doctor, "an intangible force that helps [gamblers] win or lose". He deduced that Joe Buchanan had faith in luck from his dice cufflinks and horseshoe chain. The Minotaur fed on Joe's faith in luck, killing him. (TV: The God Complex)
"Jinxing" was when someone said something similar to "what could possibly go wrong". The Doctor was known to jinx himself with such statements, and immediately regret it. (TV: Midnight, The Doctor, the Widow and the Wardrobe, Time Heist, In the Forest of the Night)
Bob Kreesus used a luck machine, which he had won gambling, on the thirteenth moon of the thirteenth planet in the Thirteenth Galaxy, in order to extract the good fortune of others, and make himself lucky. Unaware of Kresus' tampering, the Triskaidekaphobes believed themselves to be the unluckiest people in the galaxy, and feared the number 13 above all else.
When the Tenth Doctor and Rose Tyler visited on Friday 13 January 1213, they were struck by lightning, and rained on by cats. In the end, the Doctor defeated Bob Kreesus by destroying his machine. Having lost his luck, Kreesus slipped on a banana peel and fell off a cliff. (COMIC: Triskaidekaphobia)