It's an incredibly stupid movement where people are saying that they won't vote as a protest to not liking either candidate.
Usually said by people who have little to lose if Republicans win, seem to think revolution is a viable possibility if Republicans win, and/or think that by not voting something good might happen.
Also people who don't understand that our system is a First-Past-the-Post system and the only group of people who are trying to get support for not voting in this election are people on the left.
So I'm not as many words: people trying to guarantee a victory for trump.