A message board posting technique designed to end or derail threads that its user finds uninteresting or lacking productive discussion. This technique involves posting screencaps from the 1967 Spider-Man cartoon series with humorous captions unrelated to the original thread topic. The user generally initiates a Spiderman thread with captions intended to declare that the original thread topic will no longer be discussed. Occasionally, additional users contribute to the derailing with their own screencaps of Spider-Man. Frequently used on 4chan's various message boards, where the technique originated. Generally used to derail threads about incest or "wincest."
Wincest? That's a funny way to say Spiderman thread.