Antigravity
At spawn you get permanent Slow Falling and Jump Boost, so you can hop around without taking fall damage.
How It Works
Antigravity turns on by itself when you join or walk into the eligible area (spawn, by default), and turns off as soon as you leave. There's no command to start it. While it's on you jump higher, fall slowly, and take no fall damage.
If you don't want it, /antigravity toggle turns it off for your current session. It comes back the next time you join.
Commands
/antigravity toggle- toggles antigravity on or off for your current session