I think you are thinking of the movie Parenthood. That was Mr. Steve Martin and Mary Steenburgen who try to duplicate something that the Rick Moranis/(someone else) couple described doing.
Dunno if it is the same episode, but there is one where Elaine is dating a sax player, and complains that he doesn’t “do everything”. Context makes clear that “everything” is giving her oral. So eventually the guy does–between sets–then returns to the stage and can’t play the sax because his lips/tongue are…tired? Otherwise unusable? Something…think he even sputtters up a pube or something.
Also, one of those recent forgettable sitcoms–the one with the hefty guy that drives for a UPS-clone and the hot wife. She got drunk and gave him a hummer, so he plots on how to recreate the incident and comic hijinks ensue.
Movies don’t count. If it did, the infamous The Brown Bunny would have been brought up by now. (I assume Dopers are smart enough to know why this movie would come up in this thread.)
Actually, it would appear that that probably never happened. I can’t seem to find a good link to the Radar article about it, but this article from Reality Blurred discusses it. The article is about what they call “Frankenbyting” - i.e., the process of merging audio from one or more scenes with video from another to make the audience think something happened. Specifically, they allege that audio of Sarah getting a back massage from a girl was combined with fake slurping noises she never made and a shot of some trees to make you think she was going downtown in the woods.
Back in season 3 of Friends, after Ross and Rachel had broken up, there is an episode that has him pining to his ex, who is now a lesbian. (The One Without the Ski Trip) Ross goes over to Carol, his ex, and Susan’s and as Ross is talking, Carol picks at her tongue. That seemed pretty obvious to me what was being hinted. Okay, it’s 1997 but I don’t know the 1987 reference.