 Kevin Malone ( Brian Baumgartner ) overhears Oscar Martinez ( Oscar Nunez ) confessing to the camera that he is having an affair with Angela 's ( Angela Kinsey ) husband Robert Lipton ( Jack Coleman ) . Oscar makes Kevin promise not to reveal anything . During the day , Angela constantly makes unconscious double entendres and foreshadowing , sorely tempting Kevin to let out what he knows . Afraid that Kevin cannot keep his secret , Oscar tries to frame Kevin so that Toby Flenderson ( Paul Lieberstein ) will have him fired , but later confesses to him that he lied . Later , Robert visits the office , and Oscar asks unnaturally nervous around him . Before Angela 's suspicions can be aroused , Kevin interrupts to cheer Robert on about his upcoming election . Oscar says to the camera that he is proud of how Kevin kept the secret , but Kevin then reveals that he momentarily forgot all about the secret , and begins to laugh uncontrollably . 
