A disease where the afflicted individual falls hopelessly in love with another guy or girl. Symptoms can be split into first and second stage.
During the first stage, the victim becomes hopelessly obsessed. As of now, all observed first stage victims have reported a month of first stage Jack Syndrome; one extreme case reported several months. Other symptoms during first stage Jack Syndrome can include nonstop thinking about the individual, insomnia, and extraordinary increase in vitality and energy.
During the second stage, the victim's obsession over the individual decreases over time. Victims have reported experiencing second stage Jack Syndrome for anywhere between a few months to a few years. Other symptoms can include depression, increased addiction to an activity (studying, working out, playing video games, etc...), and periodic thoughts about the individual.
Greyson: I just can't stop thinking about her!
Maksi: What do you mean?
Greyson: I don't know... I haven't been sleeping cause I keep thinking about her, and I have all this energy! Yesterday, I ran 10 miles without stopping, even though I only ate breakfast.Y-y-you think something's wrong with me?
Maksi: Nah, you just have Jack Syndrome.