Season 5: Episode 111: Ray's Journal
Ray is mortified when he realizes that Marie used to read the personal journal he kept as a teenager. When Marie blurts out an embarrassing incident from Ray's past, he can't figure out how she could have possibly known that information. That is, until he discovers that she must have broken the secret code he used when writing in his journal. And in the process, his mother has learned about his most personal, and perverted, thoughts.