Spider-Man vs Firelord (shortly SM vs FL) is the way to call something inconsistent on debate forums
It's the way debaters call the concept of an outlier in the powerset of a character. Due to PIS and inconsistencies between writers, a character may sometimes perform a feat that is entirely out of their abilities when compared to their normal level of power. The term originated from a fight between Spider-Man (a Low Meta Human, who at most can destroy a building and has superhuman speed) against Firelord (a Herald of Galactus, who can casually destroy planets and can reach Faster Than Light speeds). Despite the enormous gap in power, Spider-man managed to defeat Firelord. This should have been impossible, given Spider-man's day-to-day feats of strength and durability, but it was a canon fight.
Since then SM vs FL was used in a case where a feat is considered to be out of reach of a character and has happened only once or twice in the characters' history, the SM vs FL exception is invoked and the feat is deemed invalid.
Some examples would be:
- World War Hulk beating Doctor Strange (while Strange should've murdered him)
- Red Hulk beating Silver Surfer, Uatu the Watcher and Thor with Odin Force
- Ichigo suddenly being on par with released Grimmjow, while few days before that he was stomped by one-handed base Grimmjow
- Sasuke beating Deidara
- Sasuke surviving battles against Kage (obvious PIS)
- Just every fight involving Sasuke actually