Season 9: Episode 209: Pat's Secret
Robert discovers Pat smoking and she pleads for him not to tell. Later, when Amy smells smoke on Robert, she thinks Robert smokes. Frank, Marie, Peter, Hank and Amy all think Robert smokes. Robert gets yelled at, and Pat doesn't tell the truth or back him up. The next day, Robert tells Raymond and Debra about Pat, and the family comes over. There is a bitter argument and then Debra yells out that Pat smokes. She confesses and tells the truth. There is another argument and Peter confesses something, then Hank, then Ray, then Debra. It ends with Frank and Marie telling them that they are weird and that they shouldn't do the stuff they are doing.