A gathering of people who all have the same interest.
"I'm in the Sword Art Online fandom! It's the best anime I've ever seen!"
"Fuck you"
Ligdese is a very bad illness which causes someone to die in 3 days of tumors in their groin.
"Hey dude, bad news, I have Ligdese."
"What's Ligdese?"
"Ligdese Balls."