Someone so sexually repulsive as to negate the possibility of sexual gratification of others, i.e. a male negatosexual turns straight women gay and gay men straight.
Did you see those women scatter? Mike's a negatosexual.
A person who is more attracted to celebrities of the opposite gender than that which they normally find attractive, i.e. a straight woman who finds female celebrities more attractive than male celebrities.
Megan may be straight, but the fact that she finds Emma Watson and Rachel McAdams more attractive than any particular male celebrity indicates that she is a celebisexual.