You have to be pretty smart to get picked to be a contestant on “Jeopardy!” Being well-read helps, of course, as does the ability to retain countless obscure trivial facts. You also need a fast trigger finger, as the buzzer is notoriously hard to master. And a little luck comes in handy too, as one show winner found out. But sometimes forces conspire in all the wrong ways, and all three contestants get stumped. Here are a few categories no one got right.