Tsar Bomba
Bomb spinning is a glitch that can occur in the Hariet fights in Bowsers Kingdom and Dark Side. Bomb spinning occurs when Mario hits both of Hariet's bombs back at her at nearly the same time. As a result, the second bomb will float indefinitely in the spot it hit her. It has been theorized that bomb spinning could be used to save time in speedruns by keeping a bomb to use in the next cycle, thus not needing to wait for Hariet to throw bombs the second time. https://twitter.com/NazoShade/status/1018148831161012224