Youtuber Riggs (of Riggs' Retro Challenge) has done a lot of goofy challenges on old school games - but none are as genuinely useful as this. He's worked out a (relatively) full-proof method to beating World 1-1 of Super Mario Bros. 3 - by always moving forward, and paying very close attention to the music (and singing along "jump!" at certain intervals).

It's definitely a little stressful to watch him come so close to death and not even realize it, but it's mostly just a pretty darn impressive feat.