I was playing with the new command (/effect) and when I took it off, it showed me something like walking off the Nether portal.

I took Nausea away using the /effect command.

1. Give yourself Nausea using this: /effect PLAYER_NAME 9 30 (note that it must last for a little while so it is on its full state).
2. Wait for a bit until it is on its full state (when it is cycling a lot).
3. Type: /effect PLAYER_NAME 9 0
4. Then it will act like walking off a Nether portal, I mean the purple stuff that cycles (I don't know how to say it).