How to enable slow genie effect in macOS 10.13 High Sierra?
Thanks to @etaionshrd on Reddit we have this Terminal command:

defaults write com.apple.dock slow-motion-allowed -bool true &amp;&amp; killall Dock


If it doesn't work, try copy-pasting it. There is no auto-correct in Terminal and spelling counts. Works for me macOS 10.13.2 High Sierra.

https://www.reddit.com/r/apple/comments/6jeefp/in_the_latest_high_sierra_beta_a_small_relic_from/#t1_dmpcle3