When more than one person arrives independently and nearly simultaneously at the answer to a problem or query (usu. of an arcane or perhaps geeky nature). May also be used as an interjection. Cf. jinx.
"Each of you tweeted the answer at about the same time -- it was a shasta."
Person A (shouting): "The answer is T. DeWitt Talmadge."
Person B (just as loudly, at nearly the same instant): "The Reverend Doctor Talmadge!"
Person C: "Shasta!"