Plagiarism Lawsuit Bait
An idea so obvious that it's never used, for fear of the deluge of lawsuits filed against the writer.
Back in the days when TV shows accepted unsolicited scripts, a situation came about where a certain idea was submitted so many times that the show writers couldn't use it, for fear of being hit with a plagiarism lawsuit. J. Michael Straczynski discusses this in his book on Scriptwriting, using the case of an episode of M*A*S*H where Hawkeye would be forced to operate on Trapper John to save his life. This trope still tends to rear its ugly-head when an idea is so common among fandom that the writers won't use it out of a sense of professional pride. (For example, having Wipeout or Leech use their powers on Rogue so she could have sex with Gambit.)
Hello, Unknown Troper. You'll need to get known to lend a hand here.