_ A Jeopardy contestant added a rude gesture to the typically non-offensive game show this week, when he — inadvertently, probably — gave the nation a one-finger salute while speaking to show host Alex Trebek. The moment came while Stanford student Viraj Mehta described a theorem in differential geometry that explains why folding a slice of pizza allows one to eat it more easily. In delivering his demonstration, Mehta also delivered a gesture not typically seen on the program