This feature was exclusively part of a joke version and is not currently planned for addition to regular Minecraft. It is documented here on the wiki due to being officially-released content by Mojang Studios, even if not present in a final version.
Ankle monitors were equipped in the boots slot. In survival mode, when equipped, it could not be taken off. However, players in Creative mode are unaffected.
When equipped, the player would be afflicted with Slowness I.
During the night, being a certain number of blocks from the world spawn, above a certain minimum,[check the code] would prompt the following message in chat: "CURFEW WARNING! You are violating your house arrest! Get back by [distance] meters!"
If in the Nether or the End, a different set of messages would be cycled through which can be seen in the section below.
Nether and End messages[]
CURFEW WARNING! You are violating your house arrest! Uuuh... where are you anyway?
CURFEW WARNING! Hello, are you there?
CURFEW WARNING! I'm sure you have important things to do, but you need to go back!
CURFEW WARNING! We're lonely back home!
CURFEW WARNING! By "we" I mean I. I'm lonely.
CURFEW WARNING! Ok enough games... GET BACK RIGHT NOW!
CURFEW WARNING! LAST WARNING!
CURFEW WARNING! LASTEST WARNING (really now)
CURFEW WARNING! ...
CURFEW WARNING! So... Where are you?
CURFEW WARNING! Having a good day?
CURFEW WARNING! Did you see that monster over there?
CURFEW WARNING! Give it a whack, if you would be so kind.
CURFEW WARNING! Teheee...
CURFEW WARNING! Ok, enough of this!
CURFEW WARNING! Last straw!
CURFEW WARNING! Now you die.
CURFEW WARNING! Boom!
CURFEW WARNING! Hehe, fun right?
CURFEW WARNING! Ok, you will not hear anything more from me now!
CURFEW WARNING! You'll be as lonely as I am.
CURFEW WARNING! How does that feel?
CURFEW WARNING! Stop. Please. Stupid.
CURFEW WARNING! I know, I'll wipe my memory. That way, I can start over!