Because just the idea of John Travolta schtupping Lily Tomlin is beyond absurd; they have the exact same hairstyles, and you can't tell who is who in the sex scenes.  Apparently, they both have tried to suppress it; it's only available on TV at 3AM.
Congratulations to Gil on 1000 (Original) Cinematic Posts!
Good one!!  But you forgot to mention that John Travolta's character is called 
STRIP!  I saw it at the theatre when it came out so I understand why they would want to suppress it.  
==ASIDE==Which for some reason reminds me:  Did you hear that Vivid Video is releasing a 
Jimi Hendrix sex tape?  I find it highly suspect that a film of Jimi Hendrix having sex with two women, made 40 years ago, is just now surfacing.  They say that a memorabilia collector had it in his collection.  Riiiight.  (and yes, I've ordered my copy, I remember what the Plaster-Casters said about Jimi  

)
And thanks again for the congrats!