The second (or subsequent) boyfriend from Mexico for a girl or guy who is probably white and also may have a Latin fetish. Shortening of "Next Mexican Boyfriend." Not meant in an anti-Mexican manner. See also Exican.
Susie: "I have to find a new boyfriend. Things have been dry around here since the Exican and I broke up."
Jennie: "I know a good-looking bartender. He'd be a good Nexican for you, Susie."