Fusion

A fusion is a phenomenon occurring in Super Mario Maker 2 multiplayer mode, on the flagpoles of the NSMBU and SM3DW game styles.

A fusion happens when two players' 3D models overlap when grabbing the flagpole at similar times. This happens due to the game waiting for the other players when one of them grabs a flagpole, causing several cursed images.

Fusions are usually documented by Mr. Fusion Man on raysfire's YouTube videos.