Slang term, used to mock non-asian people who are attracted to asian people. Usually of eastern descent - Chinese, Japanese, Korean etc.
Signs that someone/you has/have yellow fever include:
1) Obsession over a person of asian descent.
2) A fascination with asian stuff, e.g. Japanese things, Anime, Chinese history, Asian languages, Her parent's takeaway...
3) Acting like a prat around asian people, because you've gone into mental meltdown.
Protip: Make use of the name 'Poon' for awesome puns.
1)Yellow fever sufferer: 'Ohmygod, that *asian person* is so damn cute, I have to ask her out. I feel so lonely without her...she can make me complete <3'
Concerned friend: 'Dude, you don't know her. Why the HELL are you so obsessed with her? Please, you're scaring me.'
2) Yellow fever sufferer: 'Ohmagawd, she/he is so kawaiii!!!!1 I want to glomp him! Do u think she/he'll be impressed by mai awsum japanese/mandarin/cantonese vocab? Huh?'
3) Yellow fever sufferer: 'Oh, hi, how are you today? I just thought I'd come up and study with you here...in the library...yeah...you know, I like hong kong. I hear your family is from hong kong. Oooh, can you speak canto? Can I hear you speak canto? You do know, your hair is lovely, it's so black and nice, and your eyes too, they are lovely, so exotic and...beautiful...what? No, don't be silly, I don't fancy you, do you think I'm obsessed with azns or summat? Huh? LOLOLOOLOLOLOLOL!'