Back in 2001 or so there was a thread on the Community Board where people talked about meeting each other in the parks. It was suggested that we all pick a color to wear in the park so we could identify each other. Someone suggested that we all have ribbons of a certain color.
So a poll was put up on the CB with the different colors put on there and we all voted. Lime green came out on top. If I remember correctly, orange was second.
Not too long after that, someone reported that they had seen Mickey paint chips at Home Depot and they had used those. Well, once pictures were posted everyone wanted to do something similar, and from there it grew. People also decided that the correct Mickety paint chip taken from Home Depot should be the "alien green" Mickey.
It always tickles me that the person who created the DIS, Pete Werner, hates lime green.