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."

When you eat dirt for the first time and leave your family to build a shack in the woods

Spiderman threads are pretty much the best thing ever. The definition is self-explanatory.