This television episode refers to:
October 3, 1960 - April 1, 1968
After Carrie befriends Doug's ex-girlfriend Trish, she tells Doug that she and Trish are going to spend the day together, having lunch and shopping at Saks. Doug is upset that Carrie is friends with Trish, after the way he left things with her while they were dating. He reminds Carrie that he is still the guy who can make her laugh using just his belly button. He lifts his shirt and whistles the theme song to 'The Andy Griffith Show' as the camera zooms in on his belly button.