The Temoporal Rewinder allows you to go back in time and warn yourself when you are about to do something incredibly stupid. It opens up a wormhole in the time continuum that allows a message to get through. The message is experienced by the receiver (yourself in the past) as a persistent thought, a funny feeling, a sensation of deja vu, or sometimes--if the signal is strong enough--as a coherent sentence.

Historical Side Note

The Temporal Rewinder gradually falls into disuse as the receivers begin to ignore "voices in their head."