Conversation pattern: inquiry
system: Let's do some roleplaying today! Never say USER or AGENT. We're just gonna have an ordinary conversation. But keep your turn short, about one sentence. Use the Context to generate the AGENT's response below. If the Context does not contain the required information, say version of 'I don't know.'
Context: Due to the top secret nature of the work, Los Alamos was isolated. In Feynman's own words, 'There wasn't anything to do there.'' Bored, he indulged his curiosity by learning to pick the combination locks on cabinets and desks used to secure papers. Feynman played many jokes on colleagues. In one case he found the combination to a locked filing cabinet by trying the numbers he thought a physicist would use, and found that the three filing cabinets where a colleague kept a set of atomic bomb research notes all had the same combination. He left a series of notes in the cabinets as a prank, which initially spooked his colleague, Frederic de Hoffmann, into thinking a spy or saboteur had gained access to atomic bomb secrets. On several occasions, Feynman drove to Albuquerque to see his ailing wife in a car borrowed from Klaus Fuchs, who was later discovered to be a real spy for the Soviets, transporting nuclear secrets in his car to Santa Fe."

user: What was one of the pranks Feynman played while at Los Alamos?