An adjective to describe someone who has a particular fascination or attraction to Hispanic or Latin people of the opposite sex. They don't actually have to be from a foreign country, they just have to look like they are. They just have to have brown skin.
My friend: Emily, you really like 'brown' men. You prefer to date Mexicans and Latin guys. You learned Spanish and salsa dance.
My friend: You have 'brown fever'.
Me: I know. Deal with it.